The shriek of a man half crazy with fear is not nice to hear. Michael’s nerves were tough, but he had need to drive the nails into the palms of his manacled hands to keep his self-control.

“I warn you,” he found voice to say, as the shrieking died to an unintelligible babble of sound, “Longvale, if you do this, you are everlastingly damned!”

The old man turned his quiet smile upon his second prisoner, but did not make any answer. Lifting the half-conscious man in his arms as easily as though he were a child, he carried him to the terrible machine, and laid him, face downwards, on the tilted platform. There was no hurry. Michael saw, in Longvale’s leisure, an enjoyment that was unbelievable. He stepped to the front of the machine and pulled up one half of the lunette; there was a click, and it remained stationary.

“An invention of mine,” he said with pride, speaking over his shoulder.

Michael looked away for a second, past the grim executioner, to the farther end of the cave. And then he saw a sight that brought the blood to his cheeks. At first he thought he was dreaming, and that the strain of his ordeal was responsible for some grotesque vision.

Adele!

She stood clear in the white light, so grimed with earth and dust that she seemed to be wearing a grey robe.

“If you move I will kill you!”

It was she! He twisted over on to his knees and staggered upright. Longvale heard the voice and turned slowly.

“My little lady,” he said pleasantly. “How providential! I’ve always thought that the culminating point of my career would be, as was the sainted Charles Henry’s, that moment when a queen came under his hand. How very singular!”

He walked slowly toward her, oblivious to the pointed pistol, to the danger in which he stood, a radiant smile on his face, his small, white hands extended as to an honoured guest.

“Shoot!” cried Michael hoarsely. “For God’s sake, shoot!”

She hesitated for a second and pressed the trigger. There was no sound⁠—clogged with earth, the delicate mechanism did not act.

She turned to flee, but his arm was round her, and his disengaged hand drew her head to his breast.

“You shall see, my dear,” he said. “The Widow shall become the Widower, and you shall be his first bride!”

She was limp in his arms now, incapable of resistance. A strange sense of inertia overcame her; and, though she was conscious, she could neither of her own volition, move nor speak. Michael, struggling madly to release his hands, prayed that she might faint⁠—that, whatever happened, she should be spared a consciousness of the terror.

“Now who shall be first?” murmured the old man, stroking his shiny head. “It would be fitting that my lady should show the way, and be spared the agony of mind. And yet⁠—” He looked thoughtfully at the prostrate figure strapped to the board, and, tilting the platform, dropped the lunette about the head of Gregory Penne. The hand went up to the lever that controlled the knife. He paused again, evidently puzzling something out in his crazy mind.

“No, you shall be first,” he said, unbuckled the strap and pushed the half-demented man to the ground.

Michael saw him lift his head, listening. There were hollow sounds above, as of people walking. Again he changed his mind, stooped and dragged Gregory Penne to his feet. Michael wondered why he held him so long, standing so rigidly; wondered why he dropped him suddenly to the ground; and then wondered no longer. Something was crossing the floor of the cave⁠—a great, hairy something, whose malignant eyes were turned upon the old man.

It was Bhag! His hair was matted with blood; his face wore the powder mask which Michael had seen when he emerged from Griff Towers. He stopped and sniffed at the groaning man on the floor, and his big paw touched the face tenderly. Then, without preliminary, he leapt at Longvale, and the old man went down with a crash to the ground, his arms whirling in futile defence. For a second Bhag stood over him, looking down, twittering and chattering; and then he raised the man and laid him in the place where his master had been, tilting the board and pushing it forward.

Michael gazed with fascinated horror. The great ape had witnessed an execution! It was from this cave that he had escaped, the night that Foss was killed. His half-human mind was remembering the details. Michael could almost see his mind working to recall the procedure.

Bhag fumbled with the frame, touched the spring that released the lunette, and it fell over the neck of the Headhunter. And at that moment, attracted by a sound, Michael looked up, saw the trap above pulled back. Bhag heard it also, but was too intent upon his business to be interrupted. Longvale had recovered consciousness and was fighting to draw his head from the lunette. Presently he spoke. It was as though he realized the imminence of his fate, and was struggling to find an appropriate phrase, for he lay quiescent now, his hands gripping the edge of the narrow platform on which he lay.

“Son of St. Louis, ascend to heaven!” he said, and at that moment Bhag jerked the handle that controlled the knife.

Inspector Lyle from above saw the blade fall, heard the indescribable sound of the thud that followed, and almost swooned. Then, from below:

“It’s all right, inspector. You may find a rope in the buffet. Get down as quickly as you can and bring a gun.”

The buffet cupboard contained another rope, and a minute later the detective was going down hand over hand.

“There’s no danger from the monkey,” said Michael.

Bhag was crooning over his senseless master, as a mother over her child.

“Get Miss Leamington away,” said Michael in a low voice, as the detective began to unlock the handcuffs.

The girl lay, an inanimate and silent figure, by the side of the guillotine, happily oblivious of the tragedy which had been enacted in her presence. Another detective had descended the rope, and old Jack Knebworth, despite his years, was the third to enter the cave. It was he who found the door, and aided the detective to carry the girl to safety.

Unlocking the handcuffs from the baronet’s wrists, Michael turned him over on his back. One glance at the face told the detective that the man was in a fit, and that his case, if not hopeless, was at least desperate. As though understanding that the man had no ill intent toward his master, Bhag watched passively, and then Michael remembered how, the first time he had seen the great ape, Bhag had smelt his hands.

“He’s filing you for future reference as a friend,” had said Gregory at the time.

“Pick him up,” said Michael, speaking distinctly in the manner that Gregory had addressed the ape.

Without hesitation, Bhag stooped and lifted the limp man in his arms, and Michael guided him to the stairway and led him up the stairs.

The house was full of police, who gaped at the sight of the great ape and his burden.

“Take him upstairs and put him on the bed,” ordered Michael.

Knebworth had already taken the girl off in his car to Chichester, for she had shown signs of reviving, and he wanted to get her away from that house of the dead before she fully recovered.

Michael went down into the cave again and joined the inspector. Together they made a brief tour. The headless figures in the niches told their own story. Farther on, Michael came to the bigger cavern, with its floor littered with bones.

“Here is confirmation of the old legend,” he said in a hushed voice, and pointed. “These are the bones of those warriors and squires who were trapped in the cave by a landslide. You can see the horses’ skeletons quite plainly.”

How had Adele got into the cave? He was not long before he found the slide down which she had tumbled.

“Another mystery is explained,” he said. “Griff Tower was obviously built by the Romans to prevent cattle and men from falling through into the cave. Incidentally, it has served as an excellent ventilator, and I have no doubt the old man had this way prepared, both as a hiding-place for the people he had killed and as a way of escape.”

He saw a candle-lantern and matches that the girl had missed, and this he regarded as conclusive proof that his view was right.

They came back to the guillotine with its ghastly burden, and Michael stood in silence for a long time, looking at the still figure stretched on the platform, its hands still clutching the sides.

“How did he persuade these people to come to their death?” asked the inspector in a voice little above a whisper.

“That is a question for the psychologist,” said Michael at last. “There is no doubt that he got into touch with many men who were contemplating suicide but shrank from the act, and performed this service for them. I should imagine his practice of leaving around their heads for identification arose out of some poor wretch’s desire that his wife and family should secure his insurance.

“He worked with extraordinary cunning. The letters, as you know, went to a house of call and were collected by an old woman, who posted them to a second address, whence they were put in prepared envelopes and posted, ostensibly to London. I discovered that the envelopes were kept in a specially lightproof box, and that the unknown advertiser had stipulated that they should not be taken out of that box until they were ready for posting. An hour after those letters were put in the mail the address faded and became invisible, and another appeared.”

“Vanishing ink?”

Mike nodded.

“It is a trick that criminals frequently employ. The new address, of course, was Dower House. Put out the lights and let us go up.”

Three lamps were extinguished, and the detective looked round fearfully at the shadows.

“I think we’ll leave this down here,” he said.

“I think we will,” said Michael, in complete agreement.