The blow that Drummond had received would have broken the neck of any ordinary man. But not being an ordinary man he was only badly stunned. And he was still unconscious when he was carried out of a motorcar at Mr. William Robinson’s house in the New Forest. That his arrival was regarded as an important affair was evident from the fact that his host came himself to the front door to greet him. But from that moment it is to be feared that Mr. Robinson’s knowledge of those excellent books on etiquette which deal with the whole duty of a host towards those who honour his roof with their presence went under a slight eclipse. Regrettable to state, he did not escort his guest personally to the old oak bedroom complete with lavender-scented sheets; in fact, he even forgot himself so far as to leave him lying in the hall with his head in the coal-scuttle. But it is pleasant to state that not for long was he so remiss. At a sign from him two men picked up Drummond and carried him into his own private room, where they dropped him on the floor.

“I will make arrangements for the night later,” he remarked. “Just at present I would like to look at him from time to time, so leave him here.”

The two men went out, leaving Freyder alone with his Chief. And though he had much to tell him of importance, for a while Freyder said nothing. For there was an expression of such incredible ferocity on the benign countenance of Mr. Robinson as he stared at the motionless body on the floor that Freyder realised his presence was forgotten. For perhaps two minutes Mr. Robinson’s eyes never left Drummond’s face; then he turned to his subordinate.

“I don’t think I should ever have forgiven you, my dear Freyder,” he said softly, “if you’d had the misfortune to kill him. That supreme joy must be mine and mine alone.”

With almost an effort he obliterated Drummond from his mind, and sat down at his desk.

“Business first; pleasure afterwards. Things have evidently been happening in London. Tell me everything.”

Clearly and concisely Freyder told him what had occurred, while Mr. Robinson smoked his cigar in silence. Once or twice he frowned slightly, but otherwise he gave no sign of his feelings.

“You have no idea, then, as to how Drummond and Sir Raymond Blantyre found the house?” he asked as Freyder finished.

“Not the slightest, Chief,” he answered. “All I know is that it was Drummond who found it, and not Blantyre. Sir Raymond told me that much as I was rushing him out of the house.”

“Did he make any objections to going?”

“Not the slightest. In fact, when he realised that what he had been saying to Scheidstrun had been overheard by Drummond, his one desire was to get away as fast as he could. He apparently thought Drummond had left the house a quarter of an hour before.”

Mr. Robinson shrugged his shoulders.

“The point really is immaterial,” he murmured. “That fool Blantyre dare not speak; Drummond can’t. By the way, what has become of Scheidstrun?”

“I sent him and his wife off this evening,” said Freyder. “The pilot said he could make Brussels tonight, and finish the journey tomorrow.”

“Excellent, Freyder⁠—excellent,” said Mr. Robinson. “And the slight inconvenience of Blantyre knowing that I have not destroyed the notes is amply compensated for by the possession of our young friend here.”

“But it will mean altering our plans somewhat,” remarked Freyder doubtfully.

For a while Mr. Robinson smoked in silence, gently stroking his mutton-chop whiskers.

“Yes,” he remarked at length, “it will. Not the plans so much as the timetable. The advent of Drummond at this stage of the proceedings I must confess I did not contemplate. And since I am under no delusions as to his infinite capacity for making a nuisance of himself, the sooner he is finally disposed of the better.”

Freyder shrugged his shoulders.

“Well, Chief,” he said callously, “there he is. And there’s no time like the present.”

Mr. Robinson raised a deprecating hand.

“How coarse, my dear Freyder!⁠—how almost vulgar! My feelings against this young man are of a purely personal type. And I assure you they would not be gratified in the smallest degree by disposing of him when he was in the condition he is in now. One might just as well assault a carcase in a butcher’s shop. No, no. It will be my earnest endeavour to restore Captain Drummond to perfect health before disposing of him. Or at any rate to such a condition that he realises what is taking place. But from my knowledge of him it is a matter that cannot be postponed indefinitely. As I said before, his capacity for making trouble when confined in any ordinary house is well-nigh unbelievable.”

“Then what do you propose to do, Chief?” asked Freyder.

Given his own way now that Drummond was safely out of London and in their power, he would have finished him off then and there. To his mind Drummond was one of those unpleasant individuals who can be regarded as really safe only when they’re dead. And once granted that he was going to be killed in the near future, Freyder would have wasted no further time about it. But he knew the absolute futility of arguing with his Chief once the latter’s mind was made up, so he resigned himself at once to the inevitable.

“You are certain that you were not followed here,” said Mr. Robinson.

“As certain as anyone can ever be,” answered Freyder. “Twice I stopped the car at the end of a long, straight stretch of road and turned into a lane. There was no sign of anyone. I didn’t bother to change the tyres, since most of the road is tar macadam and there’s been no rain. And really there are so many Dunlop Magnums about now, that it’s only a waste of time.”

“And as far as I could make out, the telephone operator had no suspicions,” went on his Chief. “You did it extremely skilfully and silently. So I think, Freyder, we can assume on twenty-four hours for certain before anyone even begins to take any notice. Drummond is a man of peculiar habits, and, somewhat naturally, when I realised he was coming here, I sent a letter in his writing to that inconceivable poop Longworth. A friend of his,” he explained, seeing the look of mystification on the other’s face, “who is engaged to Miss Goodman. It states that he is hot on the trail and the postmark will be Birmingham. So I think we can certainly rely on twenty-four hours, or even forty-eight before his friends begin to move. And that will give me plenty of time to ensure that our friend upstairs has not forgotten his process. Once I am assured of that, and he has written out in a legible hand the ingredients he uses, we will delay no longer. It’s a nuisance⁠—for I detest manual labour and smells in a laboratory. And but for Drummond, as you know, we would have remained on here for six months or so, and let the old fool make the stones himself, before disposing of him finally. But since this slight contretemps has occurred, I shall have, much as I regret it, to dispense with that part of the programme. Once I know for certain that I can do it myself⁠—and I shall devote tomorrow to that exclusively⁠—we will give up this house forthwith and go on board the yacht. A good idea of mine⁠—that yacht, Freyder. There is nothing like dying convincingly to enable one to live in comfort.”

Freyder grinned, as he watched Mr. Robinson help himself to a mild whisky and soda: undoubtedly the Chief was in an excellent humour.

“We’ve run a pretty big risk this time, my dear fellow,” he went on thoughtfully. “And sometimes it almost staggers me when I think how wonderfully we’ve succeeded. But I am under no delusions as to the abilities of the English police. Once they get on to a thing they never let go⁠—and sooner or later they are bound to get on to this. Probably they will do it through Drummond’s disappearance, and Scheidstrun. Sooner or later they will track our connection with this house, and the good ship Gadfly. And then when they find that the Gadfly left England and has never been heard of again, with true British phlegm they will assume that she has sunk with all hands. And Sir Raymond Blantyre will breathe again⁠—unless they’ve put the scoundrel in prison for having suggested such an abominable crime to me; in fact, everyone will breathe again except Drummond and our friend upstairs. Oh! and Mr. Lewisham. Did you attend the obsequies on Mr. Lewisham, Freyder?”

“I did not,” laughed Freyder; and Mr. Robinson, contrary to his usual custom, helped himself to another whisky and soda.

“Yes,” he continued dreamily, “it’s a wonderful end to what I may claim without conceit has been a wonderful career. Henceforward, Freyder, my life will be one of blameless virtue.”

The other shook his head doubtfully.

“You’ll find it a bit monotonous, Chief,” he said.

Mr. Robinson smiled.

“Perhaps so⁠—but I shall give it a trial. And whenever it becomes too monotonous, I shall merely remove more money from the pockets of those two villainous men Blantyre and Leibhaus. It almost makes one despair of human nature when one realises that such cold-blooded scoundrels exist.”

“And Drummond! Have you made up your mind yet as to how you intend to dispose of him?”

“Quite simply,” replied Mr. Robinson genially. “I shall merely attach some heavy weights to his feet and drop him overboard. I am not anxious that his body should be recovered, any more than that of our other friend. That part of the affair presents no difficulties.” His eyes, grown suddenly hard and cruel, fastened on the motionless figure of Drummond, still sprawling on the floor. And suddenly he rose and bent over him with a look of anxiety on his face which changed to relief.

“For a moment I thought he was dead,” he remarked, resuming his seat. “And that would have been a real grief to me. For him to die without knowing would rob this final coup of its crown. It is the one thing needed, Freyder, to make it perfect.”

The other looked at him curiously.

“How you must hate him, Chief!”

A strange look came into Mr. Robinson’s eyes, and involuntarily Freyder shuddered. Anger, rage, passion, he had seen on many men’s faces, but never before such cold-blooded ferocity as that which showed on the face of the man opposite.

“We all have our weaknesses, Freyder, and I confess that Drummond is mine. And incredible though it may sound to you, if such a thing were possible as for me to have to choose between revenge on him and getting away with Professor Goodman’s secret, I believe I would choose the former.”

For a while he sat silent; then with a short laugh he rose. Mr. Robinson was his benevolent self once more.

“Happily the alternative is not likely to arise. We have both, my dear fellow⁠—thanks largely to your quickness and skill. And now I think I will go upstairs and see how our friend is getting on. By this time he should be very nearly ready to show me the result of his afternoon’s labours.”

“And what about Drummond?” said Freyder, eyeing him professionally. “I don’t think he’s likely to give us any trouble for the present, but it’s just as well to be on the safe side.”

Mr. Robinson turned the unconscious man over with his foot.

“Have him carried upstairs,” he ordered, “and put in one of the bedrooms. And tell off someone to look after him.” He paused by the door as a thought struck him. “And by the way⁠—let me know the instant he recovers consciousness. I’d hate to postpone my first interview with the gentleman for one instant longer than necessary.”

“Well, if I’m any judge of such matters, Chief, you’ll have to postpone it till tomorrow.”

“Then it will be a refreshing interlude in my period of tuition.”

And with a cheerful wave of his hand Mr. Robinson made his way up the stairs. It was six hours since Professor Goodman had started, and by now the clinker in the metal retort should be quite cold enough to handle. Just at first the obstinate old fool had given a little trouble; in fact, he had even gone so far as to categorically refuse to carry out the experiment. But not for long⁠—two minutes to be exact. At the end of that period a whimpering and badly hurt old man had started mixing the necessary ingredients under the watchful eye of Mr. Robinson himself. And not till they were mixed and the retort placed in the electric furnace did he leave the room.

Twice during the two hours that followed did he come back again, unexpectedly. But the old scientist’s feeble resistance was broken and the visits were unnecessary. Bent almost double he sat in his chair, with the white light from the glowing furnace falling on his face. And he was still in the same position when Mr. Robinson opened the door and went in.

The heat in the room was stifling, though the furnace had now been out for two or three hours, and he left the door open. Then without a glance at the huddled figure he strode over to the table, his eyes gleaming with suppressed excitement. For there was the retort, and after cautiously testing it with his hand to discover the temperature, he picked it up and examined it curiously.

Though he had heard the experiment described in detail by Sir Raymond Blantyre, it was the first time he had actually seen it done. The retort, still warm, was full of an opaque, shaly substance which he realised was the clinker. And inside that, like the stone inside a cherry, was the diamond. For a moment his hands shook uncontrollably; then with feverish excitement he started to chip the clinker away with a small chisel.

It broke up easily, coming off in great flakes. And as he got down deeper and deeper his excitement increased. Amongst his other accomplishments Mr. Robinson was no bad judge of diamonds in the rough; in fact, if pushed to it, he could even cut and polish a stone for himself. Not, of course, with the wonderful accuracy of the expert, but sufficient to alter the appearance of any well-known historical diamond should it come into his possession. And in the past, it may be mentioned that many had. But in this case he had no intention of bothering over such trifles. Once satisfied that the diamond was there, and that Professor Goodman had forgotten nothing, he proposed to waste no time over that particular stone. Certainly he would put it aside for future use⁠—but what was one paltry diamond to him? It was the process he wanted⁠—and the certainty that he could carry out that process himself.

Deeper and deeper went the chisel, and gradually a dreadful suspicion began to grip him. Surely by now he ought to have struck the stone itself? More than half of the clinker had come away, and still there was no sign of it. Could it be possible that the accursed old fool had made a mistake?

Feverishly he went on chipping, and at length the suspicion became a certainty. There was no diamond in the retort; nothing but valueless grey powder. The experiment had failed.

For a moment or two Mr. Robinson stood motionless, staring at the now empty retort. This was the one thing for which he had not legislated. That owing to the unusual conditions, and the strain to which Professor Goodman had been subjected, the stones might prove indifferent, he had been prepared for. But not total failure. His eyes rested thoughtfully on the huddled figure in the chair, but in them there was no trace of mercy. He cared not one whit for the obvious exhaustion of the weary old man; his sole thought was blind, overmastering rage at this further hitch in his scheme. Especially now that time had again become a dominant factor.

“This seems an unfortunate little effort on your part, my dear brother,” he remarked softly.

Professor Goodman sat up with a start.

“I beg your pardon,” he mumbled. “I’m afraid I was asleep.”

“Then you would be well advised to wake up.” He crossed and stood in front of the Professor. “Are you aware that your experiment has failed, and that there is no diamond in that retort?”

The old man sat up blinking.

“It is not my fault,” he said querulously. “How can I be expected to carry out a delicate process under such conditions, and after the abominable way I have been treated?”

“May I point out,” pursued Mr. Robinson, still in the same soft tone, “that you assured me yourself that the conditions were in every way favourable? Further that you told me yourself, as you put the retort into the furnace, that everything was all right. Since then you have had to do nothing save regulate the heat of the electric furnace.” He paused, and a new note crept into his voice. “Can it be, my dear brother, that you were lying to me?”

“It may be that the heat in the furnace was different from the one to which I have been accustomed,” answered the other, scrambling to his feet.

“May I point out that you assured me that the furnace was if anything better than your own? Further, you have a thermometer there by which to regulate the heat. So once again, dear brother, can it be that you were lying to me?” With a snarl he gripped the Professor by the arm, and shook him roughly. “Speak, you miserable old fool⁠—speak. And if you don’t speak the truth, I’ll torture you till you pray for death.”

He let go suddenly, and the Professor collapsed in his chair, only to stand up again and face the other bravely.

“A man can only die once,” he said simply. “And men have been tortured in vain for other things besides religion. To me my science is my religion. I knew you would find no diamond in the retort⁠—and you never will. You may torture me to death, you vile scoundrel⁠—but never, never, never will I tell you my secret.”

Gently, almost caressingly Mr. Robinson stroked his mutton-chop whiskers.

“Is that so?” he murmured. “Most interesting, my dear brother⁠—most interesting.” With a benevolent smile he walked over to the bell and rang it.

“Most interesting,” he continued, returning to the other man, who was watching him with fear in his eyes. “Brave words, in fact⁠—but we will see. I think you remarked before you told me the truth, that it was possibly the fault of the electric furnace. A naughty fib, dear brother⁠—and naughty fibs should always be punished. One presses this switch, I think, to start it. Yes⁠—why, I feel the warmth already. And I see that the maximum temperature registered this evening was 2,000° Centigrade. Is that you, Freyder?” he continued without turning his head, as someone entered the room.

“It is, Chief. What’s the trouble?”

“The trouble, Freyder, is that this incredibly stupid old man refuses to carry out his process for me. He has wasted six valuable hours producing a nasty-looking mess of grey powder. He has also wasted a lot of expensive electric current. And we are now going to waste a little more. I can only hope that my experiment will prove more satisfactory than his, though I greatly fear, my dear brother, that you will find it rather more painful.”

“What are you going to do?” Professor Goodman’s voice was shaking, as he looked first at his tormentor, and then at the furnace which was already glowing a dull red.

“I’m going to make quite certain,” remarked Mr. Robinson affably, “that these thermometers register correctly. I imagine that there must be a difference in the feeling of metal at 1,000° and metal at 2,000°, though both, I should think, would be most unpleasant. However, my dear Professor, you will know for certain very shortly. I see that it is just about 1,000° now. The left arm, I think, Freyder⁠—if you would be so good. And perhaps you had better turn up his sleeve: burning cloth gives such an unpleasant smell.”

A dreadful scream rang through the house, and Professor Goodman fell back in his chair almost fainting.

“Only half a second,” murmured Mr. Robinson. “And it will only be half a second at 2,000°⁠—this time. Then, dear brother, you will again carry out your process. If it succeeds⁠—well and good. If it should fail again⁠—I fear we shall have to make it a full second. And a second is a long time under certain conditions.”

Moaning pitifully. Professor Goodman lay back in his chair with his eyes closed.

“I won’t,” he muttered again and again through clenched teeth, while the heat from the furnace grew greater and greater, and the dull red changed to white.

“Foolish fellow,” sighed Mr. Robinson. “However,” he added hopefully, “it’s only half a second this time. And as a special concession I’ll let you off with only 1,900°. Now, Freyder⁠—we are quite ready.”

Freyder took a step forward, and at that moment it happened. He gave one agonised shout of terror, and then scream after scream of agony rang through the house. For it was not Professor Goodman’s arm which touched the white-hot furnace, but Freyder’s face⁠—and to his Chief’s horrified eyes it had seemed as if he had dived straight at it.

“My God!” he muttered foolishly, as Freyder, moaning horribly, dashed from the room. “How did it happen?”

The words died away on his lips and he stood staring into the shadows beyond the light thrown by the furnace. Drummond was sitting on the floor grinning vacantly at space.

“Gug, gug, gug,” he burbled foolishly. “Pretty light.”

Then, apparently bored with life in general, he returned with interest to his occupation.

“Puff⁠—puff!” he cried happily. “Puff⁠—puff! Naughty man kicked train.”

And the train which he was busily pushing along the floor consisted of his own shoes.

Once again Mr. Robinson dashed to the bell and pealed it. His momentary shock at Freyder’s ghastly accident had passed; his sole thought was that Drummond was no longer unconscious. And Drummond in full possession of his physical powers was a dangerous person to have about the place, even if his mind was wandering. But was it? That was the point. Or was he shamming? Such a possibility at once suggested itself to Mr. Robinson’s tortuous brain, and he was not a gentleman who took any unnecessary risks.

He had watched Professor Goodman totter from his chair with a look of wild hope in his face as he realised the unexpected presence of a friend; he had watched him sink back into it again with a groan as his cry for help was greeted with a vacuous grin from the man so happily playing on the floor. But still he was not satisfied, and a revolver gleamed ominously in his hand as he watched his enemy. His mind was made up on one point. Shamming or not shamming⁠—mad or sane⁠—at the slightest hint of trouble on Drummond’s part he would kill him and be done with it. In fact he was sorely tempted to do so at once: it would save a lot of bother in the long-run.

His finger tightened on the trigger, and he raised his revolver till it was pointing direct at Drummond’s heart.

“I’m going to kill you, Drummond,” he said quietly.

But if he expected to discover anything by such a test he was doomed to disappointment. Still the same vacuous grin, still the same lolling head, and a jumble of incoherent words was all the result; and very slowly he lowered his weapon, as one of his men came rushing into the room, to stop abruptly at the door as his eyes fell on the figure on the floor.

He gave a sigh of relief.

“So there you are, my beauty,” he muttered.

“Was it you who was told off to look after Captain Drummond?” said Mr. Robinson softly.

The man looked at the speaker with fear in his eyes.

“I put him on the bed, Chief,” he said sullenly, “and he was unconscious. And I hadn’t had any supper, so⁠ ⁠…”

“You went downstairs to get some,” Mr. Robinson concluded his sentence for him. “You went downstairs, you miserable fool, leaving him alone.” His eyes bored into the man’s brain, and he shrank back against the wall. “I will deal with you later,” continued Mr. Robinson, “and until then you will continue to look after him. If nothing further of this sort happens, it is possible that I may overlook your fault⁠—so you had better see to it.”

“I’ll swear it won’t happen again, Chief,” said the man eagerly. “It was only because I thought the young swine was stunned⁠ ⁠…”

With a gesture Mr. Robinson cut him short.

“You’re not paid to think, you’re paid to do what you’re told,” he remarked coldly. “Go, now, and get one of the others. And bring some rope when you return.”

The man departed with alacrity, and once more Mr. Robinson fell to staring at the man sitting on the floor. To Professor Goodman he paid not the slightest attention; all his thoughts were concentrated on Drummond. Was he shamming, or was he not? Had Freyder’s blow on the head deprived him of his reason⁠—or was it a wonderful piece of acting? And finally he decided on yet another test.

Still watching Drummond narrowly, he walked over to the door and affected to give an order to someone in the passage outside.

“Bring the girl Phyllis in here.”

Now surely there would be some telltale start if he was shamming⁠—some little movement that would give him away. But there was nothing⁠—absolutely nothing⁠—to show that Drummond had even heard. He was engrossed in some intricate shunting operations with his shoes, and after a time Mr. Robinson came back into the room. Almost, if not quite, his mind was made up⁠—Drummond was insane. Only temporarily possibly⁠—but insane. The blow on the back of his head had caused something in his brain to snap, and the man he hated most on earth was just a babbling lunatic. Almost, if not quite, he was sure of it; for certain proof he would have to wait until he could examine him⁠—and especially his eyes⁠—more closely. And Mr. Robinson had no intention of examining Drummond, sane or insane, closely until Drummond’s arms were very securely lashed together.

“You’d better be very careful of him,” he remarked as the two men came in with rope. “I am almost certain that he’s got very bad concussion, but if you handle him roughly he may get angry. I shall be covering him the whole time with a revolver, but I want you to lash his wrists behind his back.”

They approached him cautiously, and Drummond smiled at them vacantly.

“All right, old chap,” murmured the first man ingratiatingly. “Pretty train you’ve got there. Won’t you shake hands?”

“Gumph,” remarked Drummond brightly, busily pushing his shoe.

“Get hold of his other hand,” said the first man tersely to his companion. “Then we’ll get them both behind his back, and I’ll slip a running noose over them.”

Which was excellent in theory, but poor in execution. A loud crack was heard and the two men staggered back holding their heads, which had impinged with violence.

“Gumph,” again remarked Drummond. “Puff⁠—puff⁠—puff.”

“Damn the swine!” snarled the man who had originally been told off to look after him, and Mr. Robinson smiled gently. It was very obvious that, whatever his mental condition might be, Drummond’s physical strength was unimpaired.

“I think, Chief,” said the second man, “that we should do it better if we lashed his wrists in front of him to start with. It’s being manhandled that he doesn’t take to, and we might be able to slip the noose over his wrists without his realising what the game is.”

“Do it how you like,” snapped Mr. Robinson, “but do it quickly.”

Which again proved excellent in theory, but poor in execution. For it soon transpired that Drummond was far too happy playing trains on the floor to realise the desirability of having his hands lashed together. In fact the proceeding appeared to annoy him considerably. And it was not until another man had been summoned and Mr. Robinson himself had joined in the fray that they finally got the noose over his wrists and drew it tight. And in the course of doing so two of the men had crashed heavily into the furnace, which, though cooling, was still unpleasantly hot.

But at last it was done, and four panting men stood round in a ring regarding him triumphantly as he rolled on the floor. And then after a while he lay still, with a foolish grin on his face.

“Gug-gug,” he burbled. “Where’s my train?”

“I’ll gug-gug him,” snarled one of the men, kicking him heavily in the ribs. “The young devil’s a homicidal maniac.”

“Stop that!” said Mr. Robinson savagely. “All accounts with this young man are settled by me. Now stand by in case he struggles. I’m going to examine his eyes.”

They approached him cautiously, but for the moment the trouble seemed over. Like so many madmen, and people temporarily insane, his frenzied struggles of the last ten minutes had completely exhausted Drummond. And even when Mr. Robinson raised his eyelids and stared into his eyes he made no attempt to move, but just lay there smiling stupidly. For a long while Mr. Robinson examined him, and then with a nod of satisfaction he rose to his feet.

“Take him to his room, and see that he doesn’t escape again. He’s mad, but for how long he’ll remain so I can’t tell. If you see the faintest sign of his recovering his reason, come and tell me at once.”

He watched them pick up Drummond and carry him out. They took him into the next room and threw him on the bed, and Mr. Robinson followed. For a moment or two he moved restlessly on the pillows⁠—then he gave a strangled grunt and a snore.

“He’s asleep, Chief,” said one of the men, bending over him.

“Good,” answered Mr. Robinson. “Let us trust he remains so for some time.”

Then with a look of cold determination on his face he returned to the room where Professor Goodman still sat huddled in his chair.