At just about the same time that Algy Longworth was dancing on the pavement in Brook Street and demanding admission to Drummond’s house, Sir Raymond Blantyre was holding a conference with the other members of the Metropolitan Diamond Syndicate. The proceedings were taking place behind locked doors, and had an onlooker been present he would have noticed that there was a general air of tension in the room. For good or ill the die was cast, and try as they would the seven eminently respectable city magnates assembled round the table could not rid themselves of the thought that they had deliberately hired a man to commit murder for them. Not that they admitted it even to themselves⁠—at any rate, not as crudely as that. Mr. Blackton’s services had been secured to arrange matters for them with Professor Goodman⁠—to negotiate for the suppression of his discovery. How he did it was, of course, his concern, and nothing whatever to do with them. Even Sir Raymond himself tried to lull his conscience by reflecting that perhaps the drastic measures alluded to in his interview at the Palace Hotel would not be necessary. And if they were⁠—well, only a weak man wavered and hesitated once he was definitely committed to a particular line of action. After all, the responsibility was not his alone; he had merely been the spokesman for the combined opinions of the Syndicate reached after mature reflection. And if Professor Goodman was so pigheaded and obstinate, he must take the consequences. There were others to be considered⁠—all those who would be ruined.

Just at first after his return from Switzerland such specious arguments had served their purpose; but during the last two days they seemed to have lost some of their soothing power. He had found himself feverishly snatching at every fresh edition of the evening paper to see if anything had happened. He had even found himself wondering whether it was too late to stop things even now, but he didn’t know where the man who called himself Blackton could be found. From the moment when he had realised in the restaurant wagon that the old German professor and Mr. Edward Blackton were one and the same person, he had not set eyes on him again. There had been no trace of him in Paris, and no trace on the boat. He had no idea where he was; he did not even know if he was in London.

His cheque had been presented in Paris, so he had discovered from his bank only that morning. And that was the last trace of the man he had interviewed at Montreux.

“I suppose there’s no chance of this man double-crossing us.” A dark sallow man was speaking and Sir Raymond glanced up quickly. “When all is said and done he has had a quarter of a million, and we’re hardly in a position to claim it back.”

“That was one of the risks we discussed before we approached him,” said Sir Raymond. “Of course there’s a chance; that is obvious on the face of it. My impression is, however, that he will not, apart from the fact that another quarter of a million is at stake. He struck me, in a very marked degree, as being a man of his word.”

There was silence for awhile, a silence which was broken suddenly by a mild-looking middle-aged man.

“It’s driving me mad, this⁠—absolutely mad,” he cried, mopping the sweat from his forehead. “I fell asleep last night after dinner, and I tell you, I woke up shouting. Dreams⁠—the most awful dreams, with that poor old devil stabbed in the back and looking at me with great staring eyes. He was calling me a murderer, and I couldn’t stand it any more. I know I agreed to it originally, but I can’t go on with it⁠—I can’t.”

There was a moment’s tense silence, and then Sir Raymond spoke.

“I don’t understand you, Mr. Lewisham,” he said coldly. “It is quite impossible for you to back out of it now, without betraying us all. And anyway, I would be greatly obliged if you would lower your voice.”

With a great effort Mr. Lewisham controlled himself.

“Can’t we think of some other method, gentlemen?” he said. “This seems so horribly cold-blooded.”

“What other possible method is there?” snarled Leibhaus. “We’ve tried everything.”

The telephone in front of Sir Raymond rang suddenly and everyone started. It showed the condition of their nerves, and for an appreciable time the President tried to steady his hand before he picked up the receiver. And when after a few seconds he laid it down again he moistened his lips with his tongue before he trusted himself to speak.

“Mr. Blackton will be with us in a quarter of an hour, gentlemen,” he remarked, and his voice was shaking a little. “I have no idea what he wants, and I am somewhat surprised at his coming here, since I laid especial stress on the fact that we were not to be implicated in any way with his⁠—er⁠—visit to England.”

He gave a brief order through a speaking-tube; then he rose and walked wearily up and down the room. The prospect of meeting Blackton again was not at all to his taste, though his dislike was not in any way due to a belated access of better feeling and remorse. It was due to the fact that Blackton as a man thoroughly frightened him, and as he paced up and down glancing at his watch every half-minute or so he felt exactly as he had felt in years long gone by when he had been told that the headmaster was awaiting him in his study. It was useless to try to bolster up his courage by reflecting that Blackton was, after all, merely the paid servant of his syndicate. He knew perfectly well that Blackton was nothing of the sort, any more than a doctor can be regarded as the paid servant of his patient. The situation in brief was that Mr. Blackton for a suitable fee had agreed to assist them professionally, and any other interpretation of the position would be exceedingly unwise.

He started nervously as he heard the sound of voices on the stairs, but it was with a very creditable imitation of being at ease that he went forward as the door opened and Mr. Blackton was shown in. He had discarded the disguise he had worn in the train, and appeared as he had done at their first meeting in Switzerland. He nodded briefly to Sir Raymond; then coming a few steps into the room, he favoured each man present with a penetrating stare. Then he laid his gloves on the table and sat down.

“On receiving your message, I was not quite sure in which guise we were to expect you,” said Sir Raymond, breaking the silence.

“The absurd passport regulations,” said Mr. Blackton suavely, “necessitate one’s altering one’s appearance at times. However, to get to business. You are doubtless wondering at my action in coming round to see you. I may say that I had no intention of so doing until this morning. I have been in London for two days, and my plans were complete⁠—when a sudden and most unexpected hitch occurred.”

He paused and fixed his eyes on Sir Raymond.

“How many people are there who know of this discovery of Professor Goodman’s?”

“His family and our syndicate,” answered the President.

“No one else in the diamond world except the gentlemen in this room knows anything about it?”

“No one,” cried Sir Raymond. “We have most sedulously kept it dark. I feel sure I may speak for my friends.”

He glanced round the room and there was a murmur of assent.

“Then I am forced to the conclusion,” continued Mr. Blackton, “that the writer of an anonymous letter received by the Professor this morning is amongst us at the moment.”

His eyes travelled slowly round the faces of his audience, to stop and fasten on Mr. Lewisham, whose telltale start had given him away.

“I am informed,” went on Mr. Blackton⁠—“and my informant, who was cleaning the windows amongst other things at the Professor’s house, is a very reliable man⁠—I am informed, I say, that this morning the Professor received a letter stating that unless he accepted the money you had offered him, he would be killed. Now, who can have been so incredibly foolish as to send that letter?”

Mr. Lewisham fidgeted in his chair, until at length everyone in the room, noting the direction of Blackton’s glance, was staring at him.

“Was it you, Lewisham?” snapped Leibhaus.

Mr. Lewisham swallowed once or twice; then he stood up, clutching the edge of the table.

“Yes⁠—it was,” he said defiantly. “It seemed to me that we ought to neglect no possible chance of getting him to agree to our terms. I typed it, and posted it myself last night.”

Smothered curses came from all sides; only Mr. Blackton seemed unmoved.

“You have realised, of course, what will happen should Professor Goodman take that letter to the police,” he remarked quietly. “The fact that it was your syndicate that offered him the money will make it a little unpleasant for you all.”

But behind the impassive mask of his face Mr. Blackton’s brain was busy. The thing⁠—the only thing⁠—with which even the most perfectly laid schemes were unable to cope had happened here. And that thing was having a chickenhearted confederate, or, worse still, one who became suddenly smitten with conscience. Against such a person nothing could be done. He introduced an incalculable factor into any situation with which even a master-craftsman was unable to deal.

Not that he had the remotest intention of giving up the scheme⁠—that was not Mr. Blackton’s way at all. A further priceless idea had come to him since the interview at Montreux, which would render this coup even more wonderful than he had at first thought. Not only would he amass a large store of diamonds himself, but after that had been done and any further necessity for the continued existence of Professor Goodman had ceased, he would still have the secret of the process in his possession. And this secret he proposed to sell for a price considerably in excess of the two hundred and fifty thousand pounds offered to its original discoverer. After which he would decide what to do with the copy he had kept.

In fact Mr. Blackton fully realised that, in the hands of a master-expert like himself, the affair presented promises of such boundless wealth that at times it almost staggered even him. And now, at the last moment, this new factor had been introduced into the situation which might possibly jeopardise his whole carefully-thought-out scheme. And the problem was to turn it to the best advantage.

“I don’t care,” Mr. Lewisham was saying obstinately to the little group of men who were standing round him. “I don’t care if that letter of mine does stop it all. I’d sooner be ruined than go through the rest of my life feeling that I was a murderer.”

“Mr. Lewisham seems a little excited,” said Blackton suavely. “Who, may I ask, has said anything about murder?”

They fell silent, and stared at him.

“When Sir Raymond Blantyre came to me in Montreux, his request to me was to prevent the publication of this secret process of Professor Goodman’s. I stated that I would. I stated that the Professor would not give his lecture before the Royal Society. I believe that the word ‘murder’ occurred in the conversation”⁠—he gave a somewhat pained smile⁠—“but do you really imagine, gentlemen, that my methods are as crude as that?”

He carefully lit a cigar, while his audience waited breathlessly for him to continue.

“Since I find, however, that this gentleman has been so incredibly foolish and has lost his head so pitiably, I regret to state that in all probability I shall have to wash my hands of the entire business.”

Cries of anger and dismay greeted this announcement, though the anger was entirely directed against the author of the letter.

“But, really⁠—” stammered Mr. Lewisham, plucking nervously at his collar.

“You have behaved like an hysterical schoolgirl, sir,” snapped Blackton. “You have jeopardised the success of my entire plan, and apart altogether from the sending of this letter you have shown yourself to be totally unfitted to be mixed up in an affair of this description. Even if the police did treat it as a stupid hoax⁠—even, in fact, if we were able to prevent the letter being shown to the police at all⁠—you are still totally unfit to be trusted. You would probably proclaim your sin through a megaphone in Trafalgar Square, taking special care to incriminate all these other gentlemen. And so I think, since you have decided to act on your own initiative in this way, you had better undertake the affair yourself.”

He rose as if to leave, only to be, at once, surrounded by the other members of the syndicate, imploring him to reconsider his decision. And at length Mr. Blackton allowed himself to be persuaded to resume his chair. His indifference was sublime; to all outward intents and purposes he was utterly bored with the whole proceedings.

“Really, Mr. Blackton⁠—I implore of you, we all implore of you, not to desert us like this.” Sir Raymond’s eyeglass was dreadfully agitated. “Can nothing be done to counteract Mr. Lewisham’s inconceivable stupidity?”

Mr. Blackton affected to consider the point. Not for him to say that he had already decided exactly what was going to be done; not for him to say that the sole object of his recent remarks had been to produce the exact atmosphere that now existed⁠—an atmosphere of combined antagonism to Lewisham, and an uncomfortable feeling on the part of that unfortunate man that he really had made a fool of himself. And certainly not for him to say what he had decided was a meet and fit punishment for Mr. Lewisham.

He shrugged his shoulders indifferently.

“Since Mr. Lewisham has caused all this trouble,” he said carelessly, “it is up to Mr. Lewisham to endeavour to rectify it.”

A chorus of approval greeted the remark, and Lewisham leaned forward a little in his chair.

“I suggest therefore that this afternoon he should pay a visit to Professor Goodman, and find out what has happened to his letter. Should it have been handed over to the police, he must endeavour to convince the Professor that it was a stupid practical joke on his part, and persuade the Professor to ring up Scotland Yard and explain things. There will be no need for Mr. Lewisham’s name to be mentioned, if he handles the Professor tactfully. On the other hand, if the note has not been handed over to the police, Mr. Lewisham must endeavour to regain possession of it. And according to Mr. Lewisham’s report, I will decide whether I can continue in this matter or not.”

“That is tantamount to an avowal that the letter was sent by a member of our syndicate,” said Sir Raymond doubtfully. “You don’t think that perhaps it might be advisable to say that he had just discovered that some clerk had played a foolish practical joke.”

“The point seems really immaterial,” returned Mr. Blackton indifferently. “But if Mr. Lewisham prefers to say that, by all means let him do so.”

“You will go, of course, Lewisham,” said Sir Raymond, and the other nodded.

“I will go and see what I can do,” he answered. “And I can take it from you, Mr. Blackton, that there will be no question of⁠—of⁠—killing Professor Goodman?”

For a brief moment there came into Mr. Blackton’s grey-blue eyes a faint gleam as if some delicate inward jest was tickling his sense of humour.

“You may take it from me,” he answered gravely, “that nothing so unpleasant is likely to happen to Professor Goodman.”

Mr. Lewisham gave a sigh of relief.

“What time shall I go?” he asked.

Mr. Blackton paused in the act of drawing on his gloves.

“The Professor, I am told,” he remarked, “has an appointment at three o’clock this afternoon. I would suggest therefore that you should call about two-thirty.”

“And where shall I communicate with you?”

“You can leave that entirely to me, Mr. Lewisham,” murmured the other, with an almost benevolent smile. “I will take all the necessary steps to get in touch with you. Well, gentlemen”⁠—he turned to the others⁠—“that is all, I think, for the present. I will report further in due course. By the way, Mr. Lewisham, I wouldn’t give your name to the servant, if I were you.”

With a slight bow he opened the door and passed down the stairs. He paused as he reached the crowded pavement and spoke two words to a man who was staring into a shopwindow; then he deliberated whether he should call a taxi, and decided to walk. And as he strolled along⁠—slowly, so as not to destroy the aroma of his cigar, his reflections were eminently satisfactory. If the police had not received the note, he was in clover; if they had, a little care would be necessary. But in either case the one detail which had previously been, if not lacking, at any rate not entirely satisfactory was now supplied. It gratified his intellect; it pleased his artistic sense. Just as the sudden and unexpected acquisition of a tube of some rare pigment completes a painter’s joy, so this one detail completed Mr. Blackton’s. That it consisted of a singularly cold-blooded murder is beside the point: all artists are a little peculiar. And if fool men write fool letters, they must expect to suffer small annoyances of that sort. After all, reflected Mr. Blackton with commendable thoughtfulness, the world would endure Mr. Lewisham’s departure with almost callous fortitude.

He realised suddenly that he had reached his destination, and throwing away his cigar he produced his latchkey and entered the house. It was situated in one of those quiet squares which lie, like placid backwaters, off the seething rivers of London. And its chief point of interest lay in the fact that it formed the invariable pied-à-terre of Mr. Blackton when visiting England in whatever character he might at the moment be assuming. It appeared in the telephone-book as belonging to William Anderson, a gentleman who spent much of his time abroad. And it was to William Anderson that the Inland Revenue were wont yearly to address their friendly reminders as to the duties of British citizens. Ever mindful of those duties, Mr. Anderson had declared his income at nineteen hundred and fifty pounds per annum, and had opened a special account at a branch bank to cope with the situation. He drew the line at admitting his liability to supertax; but after mature reflection he decided that his method of life rendered it advisable to state that his income was unearned.

He placed his gloves and stick on the table in the hall, and slowly ascended the stairs. A few little details still required polishing up in connection with his afternoon’s work, and he was still deep in thought as he entered a room on the first landing.

A man was seated at a desk, who rose as he entered⁠—a man whose face was well-nigh as inscrutable as his chief’s. He was Mr. Blackton’s confidential secretary, Freyder, a man with a salary of ten thousand a year plus commission. He was as completely unscrupulous as his employer, but he lacked the wonderful organising brain of the other. Given a certain specific job to do, he could carry it out to perfection; and for making arrangements in detail he was unrivalled. Which made him an ideal staff officer⁠—a fact which the other had very soon recognised. And because Edward Blackton, like all big men, was not such a fool as to underpay an almost invaluable subordinate, he took care that Freyder’s salary should be such that he would have no temptation to go. For it he demanded implicit obedience, no mistakes, and at times twenty-four hours’ work out of twenty-four.

“What did you find out, Chief?” he asked curiously.

“It was sent by one of them, as I suspected,” answered Blackton, seating himself at his desk. “A stupid little man called Lewisham, who appears to have lost his head completely. However, on my assuring him that I had no intention of killing the excellent Goodman, he agreed to go round this afternoon and talk to the Professor about the matter.”

“Go round this afternoon?” echoed Freyder, surprised. “What do you want him there for, this afternoon?”

Blackton smiled gently.

“He happens to be about the same size as our worthy Professor,” he murmured, “so it struck me he would come in very handy. By the way, make a note, will you, to obtain a specimen of his writing and signature. Find out if he’s married, and, if so, draft a letter to his wife from him saying that he’s gone to Valparaiso for the good of his health. Have it sent out to Number 13, and posted there.”

He stared thoughtfully out of the window, and Freyder waited for any further instructions.

“Anything more to be settled about the house?”

“Everything fixed, Chief; it’s ready to move straight into this afternoon.”

The telephone bell rang on Freyder’s table.

“Good,” he remarked a few moments later, replacing the receiver. “Number 10 reports that he followed Goodman to St. James’s Square; that he is now having lunch at the Junior Sports Club, and that he has not communicated verbally with the police.”

“And since the letter was in his pocket when he left his house, presumably he has not communicated in writing. He must be a frivolous old man, Freyder, to lunch at such a club. Anyway, I trust he will have a substantial meal, as I’m afraid his constitution may be tried a little during the next few hours.”

He glanced at his watch. “The box and the men are ready?”

“Loaded up on the car at the garage.”

“Excellent. Then I think a pint of champagne and a little caviar⁠—and after that I must get to work. And we will drink a silent toast to the worthy Mr. Lewisham for his kindly forethought in being much the same size as the Professor, and wish him bon voyage to⁠—what did I say?⁠—oh! yes, Valparaiso.”

“I don’t quite get Mr. Lewisham’s part in this show, Chief,” remarked Freyder.

Mr. Blackton positively chuckled.

“No more does he, my good Freyder⁠—no more does he. But I can positively assure you of one thing⁠—he is not going to Valparaiso.”

And he was still chuckling ten minutes later when he rose and passed into an inner room at the back. It was a strange place⁠—this inner sanctum of Mr. Edward Blackton. The window was extra large, and was made of frosted glass which effectually prevented any inquisitive neighbour from seeing in. Around the walls full-length mirrors set at different angles enabled him to see himself from every position⁠—an indispensable adjunct to making up on the scale he found necessary. A huge cupboard filled one wall of the room, a cupboard crammed with clothes and boots of all sorts and descriptions; whilst on a shelf at the top, each in its separate pigeonhole, were half a dozen wigs. But the real interest of the room lay in the small dressing-table which he proceeded to unlock. A score of little bottles containing strange liquids, brushes, instruments, lumps of a peculiar putty-like substance, were all most carefully arranged on shelves. And it was the contents of this table far more than any change of clothes that enabled him to make such extraordinary alterations in his personal appearance. Literally, when seated at that table, he could build himself a new face. He could change the colour of his eyes, he could alter the shape of his nose. A judicious stain could turn his normally perfect teeth into unpleasant, badly kept ones; whilst on the subject of dyes for hair and eyebrows he could have written a textbook.

It was three-quarters of an hour before the door opened again and the snuffling old German of the restaurant wagon emerged. Professor Scheidstrun was ready to discuss the atomic theory with Professor Goodman with special reference to carboniferous quartz. Outside the door a motorcar was standing with a large box on board containing his specimens; while by its side were two men who were to lift the box off the car, and in due course lift it on again. And the only other thing of interest which might be mentioned in passing is that if Frau Scheidstrun had happened to see him getting into the car wheezing peevishly in German, she would undoubtedly have wondered what on earth her husband was doing in London⁠—so perfect was the makeup. But since that excellent woman was chasing the elusive mark in Dresden at the moment, there was but little fear of such an unfortunate contretemps.

It was at twenty past two that he arrived at Professor Goodman’s house. As he stepped out of the car a man walked quietly towards him, a man who stopped to watch the big box being carefully lowered to the ground. He stopped just long enough to say, “No one in the house except the servants,” and then he strolled on.

With great care the two men carried the box up the steps and, considering the contents were lumps of carboniferous quartz, the intense respect with which they handled it might have struck an onlooker as strange. But the parlourmaid, grown used through long experience to the sudden appearance of strange individuals at odd hours, merely led the way to the laboratory, and having remarked that the Professor might be back at three, or possibly not till six, according to whether he had remembered the appointment or not, she returned to her interrupted dinner.

“Get the box undone,” said Blackton curtly. “But don’t take anything out.”

The two men set to work, while he walked quickly round every corner of the room. Of necessity a little had had to be left to chance, and though he was perfectly capable of dealing with the unexpected when it arrived, he preferred to have things as far as possible cut and dried beforehand. And at the moment what he wanted to find was a cupboard large enough to accommodate a man. Not that it was absolutely necessary, but it would assist matters, especially in the event of the Professor bringing a friend with him. That was a possibility always present in his mind, and one which he had been unable to guard against without running the risk of raising the Professor’s suspicions.

He found what he wanted in a corner⁠—a big recess under the working bench screened by a curtain, and used for old retorts and test-tubes. It was ideal for his purpose, and with a nod of satisfaction he went over to the door. All was well⁠—the key was on the inside; and with one final glance round the room the exponent of the new atomic theory sat down to wait.

Before him lay the riskiest thing he had ever done in all his risky career, but had anyone felt his pulse he would have found it normal. And it wasn’t of the next hour that Mr. Blackton was thinking so much, but of the future, when his coup had succeeded. That it would succeed was certain; no thought of failure was ever allowed to enter his mind.

Five minutes passed⁠—ten⁠—when the ringing of the front-door bell brought him back from dreams of the future. This must be Mr. Lewisham, and with his arrival came the time for action. Blackton listened intently⁠—would he be shown into the laboratory or into some other room? If the latter, it would necessitate getting him in on some pretext; but steps coming along the passage settled that point. Once more the door was flung open by the parlourmaid; once more she returned to better things in the servants’ hall.

Lewisham paused, and glanced a little doubtfully at the old German in his dirty black clothes. Some chemical friend of the Professor’s evidently; possibly it would be better to wait somewhere else. He half turned to the door as if to go out again, when suddenly he felt two hands like bars of steel around his throat. For a moment or two he struggled impotently; then he grew still. And after a while the limp body slipped to the floor and lay still.

“Underneath that bench with him,” snapped Blackton. “Quick.”

He had opened the door an inch or two and was peering out. The passage was empty, and faint sounds were coming up the stairs from the servants’ quarters.

“Stay where you are,” he said to the two men. “I shall be back in a minute.”

He walked along the passage towards the front door, which he opened. Then he deliberately rang the bell, and stood for a few seconds peering out. And it was not until he heard the footsteps of the parlourmaid that he shut the door again with a bang, and advanced towards her, gesticulating wildly.

“Where is your master?” he cried. “I must to my business get; I cannot here the whole day wait. That other gentleman⁠—he does not wait. He go. I too⁠—I follow him.” He glanced at the girl. “Speak, woman.” He waved his arms at her, and she retreated in alarm. “I will take my specimens, and I will go⁠—like him.”

Still muttering horribly under his breath, he walked up and down the hall, while the parlourmaid endeavoured to soothe him.

“I expect the Professor will be back soon, sir,” she murmured.

“Soon,” he raved. “I who have come from Germany him to see, and then I wait. He write to me: I write to him⁠—and then I come with my specimens. And you say soon. Nein⁠—I go. I go like that other.”

It was at that moment that the front door opened and Professor Goodman entered.

“A thousand apologies, my dear Professor,” he cried, hurrying forward. “I fear I am late⁠—very late. I hope I have not kept you waiting.”

He led the other towards the laboratory, and the parlourmaid made hurried tracks for safety.

“No wonder that there other one wouldn’t wait,” she remarked to the cook. “He’s a holy terror⁠—that German. Dirty old beast, with egg all over his coat, waving his arms at me. Old Goodman is a pretty fair freak, but he does wash. I ’opes he enjoys himself.”

Which was a kindly thought on the part of the parlourmaid. And the fact that it was expressed at the exact moment that Professor Goodman went fully under the influence of an anaesthetic may be regarded as a strange coincidence. For there was no time wasted in the laboratory that afternoon. Much had to be done, and hardly had the door closed behind the master of the house when he found himself seized and pinioned. One feeble cry was all he gave; then a pad soaked in ether was pressed over his nose and mouth, and the subsequent proceedings ceased to interest him.

Very interesting proceedings they were too⁠—that went on behind the locked door. Bursts of German loquacity with intervals of a voice astonishingly like Professor Goodman’s would have convinced any inquisitive person listening outside the door that the two savants were in full blast. Not that anyone was likely to listen, but Blackton was not a man who took chances. And it takes time to change completely two men’s clothes when one is dead and the other is unconscious. One hour it was, to be exact, before the body of Mr. Lewisham dressed in Professor Goodman’s clothes, even down to his boots, was propped up in a chair against the bench, with various bottles and retorts in front of him. One hour and a quarter it was before a number of small packets had been taken from the big wooden case and stacked carefully on the bench so that they touched the dead man’s chest. One hour and a half it was before the still unconscious Professor Goodman was placed as comfortably as possible⁠—Mr. Blackton had no wish to run any chances with his health⁠—in the big wooden case, and nailed up. And during the whole of that hour and a half the discussion on carboniferous quartz had continued with unabated zest.

At last, however, everything was finished, and Blackton took from his pocket a little instrument which he handled very gingerly. He first of all wound it up rather as a Bee clock is wound, and when it was ticking gently he placed it in the centre of the heap of small packets. Then he unlocked the door.

“Put the box on the car,” he ordered. “Then pick up Freyder, and go straight to the house.”

Once again the two men staggered down the passage with their load, while Blackton glanced at his watch. Just a quarter of an hour to put through⁠—before things happened. He closed the door again, and once more his guttural voice was raised in wordy argument for the benefit of any possible audience. And in the intervals when he ceased only the faint ticking broke the silence. Everything had gone without a hitch, but there were still one or two small things to be done. And the first of these showed the amazing attention to detail which characterised all his actions. He took the key from the door and put it on the desk; a master-key of his own would enable him to lock the door from outside, whereas the presence of the key in the room would make it appear that it had been locked from within. And it was precisely that appearance which he wished given.

Once more he looked at his watch: ten minutes to go. Nervous work, that waiting; and even he began to feel the strain. But he daren’t go too soon; he daren’t leave too long a space of time between the moment he left the house and the moment when the ticking would cease. And he didn’t want to go too late, because the last thing he desired was to be on, or even too near, the premises when the ticking ceased. Moreover, there was always the possibility of a flaw in the mechanism. Morelli was a wonderful craftsman, and he had staked his reputation on it taking exactly a quarter of an hour. But even so⁠—it was nervous work, waiting.

Precisely five minutes later⁠—and they were the longest five minutes Mr. Blackton had ever spent in his life⁠—he pressed the bell. His guttural voice was raised in expostulation and argument as the parlourmaid knocked at the door. Still talking, he opened it himself, and over his shoulder the girl got a fleeting glance of Professor Goodman engaged in one of his experiments to the exclusion of all else.

“My hat, girl,” cried the German, waving his arms at her. She went to get it, and from behind her back came the noise of a key turning. “Ach! my friend⁠—no one will disturb you,” rumbled the German. “No need to your door lock.” Mechanically he took the hat the parlourmaid was holding out, while he still continued muttering to himself. “What is the good? one mistake, and you will experiment no more. You and your house will go sky-high.”

Still waving his arms, he shambled off down the street, and the girl stood watching him. And it was just after he had turned the corner and she was expressing her opinion of his appearance to the cook, who was taking a breather in the area below, that she was hurled forward flat on her face. A terrific explosion shook the house; windows broke; plaster and pictures came crashing down. And if it was bad in the front, it was immeasurably worse at the back. A huge hole had been blown in the outside wall of what had once been the Professor’s laboratory; the three inside walls had collapsed, and the ceiling had descended, bringing with it a bed, two wardrobes, and a washing-stand complete.

In fact there was every justification for the remark of the parlourmaid as she picked herself up.

“Lumme! what’s the old fool done now? I suppose he’ll ring the bell in a minute and ask me to sweep up the mess.”

An hour later Edward Blackton was seated at his desk in the house in the quiet square. Up to date his scheme had gone even more smoothly than he had expected, though there were still one or two small points to be attended to before he could retire from observation and devote himself to the Professor. There was bound to be an inquest, for instance, and he was far too big a man not to realise that it might be fatal for him not to attend it. Moreover, there was the little matter of that extra quarter of a million from the Metropolitan Syndicate.

But just at the moment Lewisham was occupying his mind. A note in cipher on the table in front of him from Freyder informed him that Henry Lewisham was a married man, and that he lived in South Kensington. And since the appearance of the late Mr. Lewisham betokened his immense respectability, there was but little doubt that Mrs. Lewisham would become seriously alarmed if her spouse absented himself for the night from the conjugal roof without any word to her.

Blackton pressed a bell on his desk twice, and a moment or two later the man who had been staring into the shopwindow, and to whom he had spoken as he left the Metropolitan Syndicate earlier in the day, entered.

“That man you followed this morning⁠—Lewisham: did he go home to lunch?”

“No, Chief. He had a chop in a restaurant in the city.”

“Did he use the telephone as far as you know?”

“I know he didn’t use it. He was never out of my sight from the time he came into the street till he went into Goodman’s house.”

Blackton nodded as if satisfied.

“Go to Euston, and send a wire to this address. ‘Called North on urgent business, Henry.’ Then go to the Plough Inn in Liverpool, and wait there for further orders. Draw fifty pounds for expenses”⁠—he scribbled his signature on a slip of paper⁠—“and it is possible you will have to start for South America at a moment’s notice. If you do, it will be necessary for you to make yourself up to an approximate resemblance of Henry Lewisham, and your berth will be taken in his name.”

“I didn’t have a chance of studying his face very closely, Chief,” said the man doubtfully.

Blackton waved his hand in dismissal.

“Approximate resemblance, I said,” he remarked curtly. “You will receive full instructions later. Go.”

He lay back in his chair as the door closed behind the man, and pulled thoughtfully at his cigar. A merciful fact, he reflected, that it is not a police offence for a man to run away from his wife. In fact if Mrs. Lewisham was anything like Mr. Lewisham, it could hardly be regarded as an offence at all by any disinterested person, but rather as an example of praiseworthy discretion. A letter in due course from Liverpool stating his intention; a resemblance efficient to cope with a wireless description in case the lady should think of such a thing⁠—and finally complete disappearance in South America. An easy place to disappear in⁠—South America, reflected Mr. Blackton; a fact he had made use of on several occasions, when the circumstances had been similar. And it was better for sorrowing relatives to picture their dear one alive and wandering through primeval forests in Brazil, or dallying with nitrates in Chile, than for them to realise that the dear one was very, very dead. It was also better for Mr. Blackton.

He dismissed the unfortunate Lewisham from his mind, and produced from his pocket the papers he had taken from Professor Goodman before removing his clothes. The first thing he saw, to his intense satisfaction, was the warning typewritten letter, and holding a match under one corner of it he reduced it to ashes and finally to powder. Two or three private letters he treated similarly, and then he came to a dozen loose sheets of paper covered with incomprehensible scrawling hieroglyphics. These he carefully pinned together and put in his pocket, reflecting yet again on the extreme goodness of fate. And then for the second time he took from the drawer where he had placed it for safety the metal retort which apparently played such an important part in the process. He had found it standing on the electric furnace in the Professor’s laboratory, and now he examined it curiously. It was about double the size of an ordinary tumbler, and was made of some dull opaque substance which resembled dirty pewter. And as Blackton looked at it and realised the incredible fortune that was soon to come to him out of that uninteresting-looking pot, his hand shook uncontrollably.

He replaced it in the drawer, as someone knocked on the door. It was the man who had spoken to him outside the Professor’s house.

“They’re all humming like a hive of bees, Chief,” he remarked. “The police are in, and they’ve cleared away the debris. I managed to get in and have a look⁠—and it’s all right.”

“You’re certain of that,” said Blackton quietly.

“There’s nothing left of him, Chief, except a boot in one corner.”

Blackton rubbed his hands together.

“Excellent⁠—excellent! You’ve done very well: cash this downstairs.”

Again he scribbled his initials on a slip of paper, and pushing it across the table dismissed the man. Assuredly luck was in, though as a general rule Blackton refused to allow the existence of such a thing. The big man, according to him, made allowance for every possible contingency; only the fool ever trusted to luck if anything of importance was at stake. And in this case he only regarded his luck as being in because he would be able, as far as he could see, to carry on with the simplest of the three schemes which he had worked out to meet different emergencies should they arise. And though he had employed enough explosive to shatter ten men, no man knew better than he did how capricious it was in its action.

Now he was only waiting for one thing more⁠—a telephone call from Freyder. He glanced at his watch: hardly time as yet, perhaps, for him to have reached his destination and to get through to London. In fact it was twenty minutes before the bell rang at his side.

“Everything gone without a hitch.”

Freyder was speaking, and with a gentle sigh of pure joy for work well and truly done Mr. Blackton laid down the receiver.

Half an hour later he was strolling along Pall Mall towards his club. A newsboy passed him shouting “ ’Orrible explosion in ’Ampstead,” and he paused to buy a copy. It had occurred to him that it is always a good thing to have something to read in the cooler rooms of a Turkish bath. And he never went into the hotter ones; there were peculiarities about Mr. Edward Blackton’s face which rendered great heat a trifle ill-advised.