Geoffrey had not long to wait. From where he was standing he could see down into the vault perfectly well. He would have been better satisfied had he understood what those people were talking about, but their words conveyed nothing to him.

On the floor of the vault the queer-looking machinery was spread out, and to the ends of the india-rubber tubes wires were attached. No sooner had this been accomplished than the woman, after giving some rapid instructions to her allies, left the vault. She was so quick that Geoffrey barely had time to conceal himself behind a pillar before she passed him.

The woman was masked and disguised beyond recognition, but Geoffrey had no need to be told who she was. He knew that he was in the presence of Mrs. May. And, despite his knowledge of her cleverness and resource, he found himself marveling to see her display so fine a knowledge of the house.

The woman passed along, dragging a number of fine light wires after her. The other ends of the wires were attached to the queer-looking apparatus in the vault.

Mrs. May went along the passages, along the corridor, and up the stairs as if she had been accustomed to the house all her life. Surely she must have been here many times before, or she would not have exhibited such fearless confidence. The idea of the black, gliding figure creeping about the house in the dead of night filled Geoffrey with loathing.

All the same, he did not neglect his opportunities. He followed swiftly and silently until he came to the main corridor on the first landing. Here, to his surprise, the woman turned into one of the bed-rooms, the room used by the head of the house. She closed the door behind her.

What to do next? But Geoffrey was not long in doubt. Ralph was standing by his side, a dark lantern in his hand.

"Where did she go?" he whispered.

"You heard her, then?" asked Geoffrey.

"Of course, I heard everything. I see with my ears. Naturally you guessed who she was. But what room did she go into?"

"My grandfather's."

"So I expected. But she means to visit all the rooms in turn. You need not be afraid, she will be there for some minutes. What do you see outside?"

Geoffrey made a close examination with the lantern.

"I see a tangle of small wires on the floor," he said. "They come up from the vaults."

"Where they are attached to a queer-looking instrument?"

"Yes, yes. I see you know all about it. One of the wires runs under the door into the room where Mrs. May is engaged."

"And where she will be engaged for some time," said Ralph. "Move that book ladder and look over the fanlight."

There were books on high shelves in the corridor, and a light librarian's ladder close at hand. Geoffrey propped this against the door and looked in through the open fanlight. All the bed-room doors had fanlights at Ravenspur.

The lantern inside was on the dressing-table and, standing on a chair by a fireplace, was Mrs. May. She had pinned the thin wire to the wall cunningly, and had turned the end of it into a plate that stood on the mantel shelf. From a flask she poured a little white powder into the plate.

This done she seemed to be satisfied. Geoffrey whipped the ladder away and the woman emerged from the room. Once more she went along the corridor with firm, resolute step, and the air of one who knows what she is doing and has a definite object in view.

From one bed-room to another she went, leaving a wire in each until every room occupied by one of the Ravenspur family had been visited. Geoffrey's room was the last. When she had finished here she took up a pair of scissors and tapped the wire. Outside the door Geoffrey and Ralph could hear the noise distinctly.

Ralph's jaws came together with a click.

"The key is outside your room door," he whispered. "Turn it."

Geoffrey wondered, but he hastened to comply. The key turned with an ease and silence that testified to the fact of its having been carefully oiled.

"What does it all mean?" Geoffrey whispered.

"She is going to test her machinery," said Ralph with a chuckle. "And she is going one step farther to her own destruction. Listen."

Again came the faint tap, and then down from far below the purring jar of electrical apparatus in motion. There was silence inside the room for a moment and then Geoffrey saw the handle turn. It was turned softly at first, then more quickly, and finally it was tugged as an angry child snatches at a toy.

Ralph chuckled. The diabolical mirth seemed to come deep from his throat.

"She is trying to get out," Geoffrey whispered.

"Of course she is," Ralph replied. "But not quite yet."

The lock was rattling loudly by this time; there was a half-angry, half-frightened muttering from within. And then there came a long, piercing, wailing scream, as of a woman in the last agony before death.

Geoffrey would have started back, but Ralph restrained him.

"No, no," he whispered violently. "It is all right; everything is turning out splendidly."

"But she is a woman and in deadly peril, uncle."

"I know it, lad. Five minutes more and that fiend will be beyond further mischief. She has been trying the effect of her infernal contrivance and will be hoist with her own petard. She is scared to death. She imagines she has fastened herself in and can't get out."

"But this is murder," Geoffrey cried.

"I dare say some people would call it so," Ralph replied coolly. "As a matter of fact, there never could be homicide more justifiable than to let that woman perish there. Still, we are not going to do anything of the kind. When those cries cease, and you hear yonder wretch fall to the ground, then open the door and drag her out."

The cries were coming wildly from behind the door; there was a hammering on the panels. The cries rang through the house, they reached the Asiatics in the vaults and the latter fled in terror into the night.

Something had happened, but what it was they did not care. They had only themselves to think of.

In spite of his strong nerves, Geoffrey shuddered. It was horrible to be alone in that grim house of tears, waiting in the darkness, opposed by grim horrors and, above all, to have that note of agony ringing in his ears.

Would it never stop? Would the time to act never come? Geoffrey would have interfered in spite of everything but for the fact that Ralph was gripping his shoulder in a grasp that at any other time would have been painful.

Suddenly the noise ceased. There was a moan and the soft, crushing fall of a body. Ralph's face blazed up instantly.

"Now," he cried, "there is no time to be lost."

Geoffrey darted forward. He had the door opened in an instant. Mrs. May lay still and white on the floor. The atmosphere of the room seemed to have vanished. It was intolerable to breathe there; air there was none.

As the door fell back the room filled as with a sudden strong draught. Geoffrey dragged the unconscious figure into the corridor.

"Will she die?" he gasped.

"No, she will not die," Ralph said coolly. "Had I intended her to die I should not have allowed you to open the door. Pick her up and throw her on one of the beds in a spare room. She will require no attention, but she will not attain consciousness for some hours. And, after that, she will be useless for a day or two. You need not worry; our scheme is working out splendidly. Pick her up."

Ralph indicated the still figure with brutal indifference. He would have shown more consideration to a sick dog. Geoffrey complied, and presently made the woman as comfortable as circumstances allowed.

Geoffrey had hardly done so before there was a light footfall in the corridor, and Tchigorsky appeared, still in disguise.

"I gather that things are well," he said. "Just now I met that she-devil's accomplices fleeing as if the Father of Lies was behind them. She was trapped, eh?"

Ralph nodded and chuckled.

"In Geoffrey's room," he explained. "When she was testing her apparatus I had the key turned on her. And she could not get out. I let her remain there as long as I considered it safe to do so, and her yells must have alarmed her confederates. Probably they have fled, leaving things intact."

"Probably," said Tchigorsky. "I will go and see."

He was back again presently, a pleased expression on his face.

"Nothing has been touched," he said. "I have removed the wires, in case of danger. We have the lady more or less under our thumb."

"What was she doing?" Geoffrey asked.

"It is an appliance for exhausting air," Tchigorsky explained. "You take a powder and place it on a hot plate. Directly it begins to burn it draws up all the air. The thing has been known in the East for thousands of years. Mrs. May applied electricity to give her greater scope. A plate of the powder was to be heated in the room of everybody in the castle when asleep.

"A few minutes and the thing is done. Then the wires are withdrawn and gradually the different rooms fill with air again. The burnt powder leaves no trace. Then you are all found dead in your beds and nobody knows how it is done. The wires are easily drawn back to the battery and the whole thing is destroyed."

Geoffrey shuddered.

"What a fiend!"

CHAPTER XLVI
NEARING THE END

It was some time before any one spoke. Geoffrey was turning the whole matter over in his mind. He was still puzzled.

"I don't understand it," he said. "Of course, I follow all you say, and I see the nature of the plot intended to end us all at one fell swoop. But why do you want to have that woman under the roof?"

"Because so long as she is under the roof she is comparatively harmless," Tchigorsky explained. "The princess is hot and vengeful and passionate, but she has her vein of caution and will take no unnecessary risks. She will be bewildered and will not know whether she had been suspected or not. The more cordial to her you are the more suspicious she will be. Of course, she will make up some plausible tale to account for her intrusion, and, of course, you must pretend to believe it. It will be impossible to move her for a day or two, and here I come in."

"In what way?" Geoffrey asked.

"In the way of having a free hand," Tchigorsky said, with a smile. "The princess will be cut off from her allies, and I shall be able to ransack her private papers for one thing."

Geoffrey nodded. He began to see the force of Tchigorsky's clever scheme. And then the cold solitude of the house struck him. For a moment he had forgotten all about the family still on the beach and the agony they were suffering on his account.

"I suppose you can do no more to-night?" he asked.

"I am not so sure of that," Tchigorsky said dryly. "Meanwhile I can safely rest for an hour or so. I am going to lie hidden in Ralph's bedroom for the present and smoke his tobacco. Do you want anything?"

"I should like to relieve the minds of my friends," said Geoffrey.

"That of course," Tchigorsky responded. "Go at once. You were picked up by a passing boat – or yacht – that landed you at Manby. You walked back and when you got home to change your clothes you found the place deserted. Don't say anything as to Mrs. May. Your Uncle Ralph will have that story to tell when you return. You are not to know anything about Mrs. May."

"All right," Geoffrey said cheerfully. "Now I'll be off."

He made his way down the cliffs unseen. There were lanterns flitting about the shore; he could see the flash of Marion's white dress and Vera by her side. He came gently alongside them.

"Vera," he said. "What is all this about?"

Vera turned and gave a cry. She was acting her part as well as possible, and the cry seemed genuine. But the tears in her eyes were tears of thankfulness that the sufferings of those dear to her were ended. She clung to her lover; her lips pressed his.

Marion stood there white and still as a statue. The girl seemed to be frozen. Geoffrey's touch thawed her into life again.

"Geoffrey!" she screamed, "Geoffrey! Thank God, thank God! Never again will I – "

With another scream that rang high and clear, the girl fell unconscious at his feet. He raised her up tenderly as the others came rushing forward. There was a babel of confused cries, hoarse cheers, and yells of delight. The villagers were running wild along the sands. Scores of men pressed eagerly round to shake Geoffrey's hand.

"I was picked up by a yacht," he said. "Of course I know there was foul play. I know all about the broken mast and the sawn oars. You may rest assured I will take more care another time. And I was – "

Geoffrey was going to say that he had been warned, but he checked himself in time. His progress toward home was more or less a royal one. It touched him to see how glad people were. He had not imagined a popularity like this.

Vera clung fondly to his arm; Rupert Ravenspur walked proudly on the other side. Not once had the old man showed the slightest sign of breaking down, but he came perilously near to it at the present time. Marion held to him trembling. She felt it almost impossible to drag herself along.

"You are quaking from head to foot," said Ravenspur.

"I am," Marion admitted. "And at the risk of increasing your displeasure I should say you are very little better, dear grandfather. I fear the shock of seeing Geoffrey after all this fearful suspense has been too much for you."

Ravenspur admitted the fact. He was glad to find himself at home again, glad to be rid of the rocking, cheering crowd outside, and glad to see Geoffrey opposite him. Marion, pale as death, had dropped into a chair.

"I am going to give you all some wine," said Geoffrey. "You need it. Please do not let us discuss my adventure any more. Let us drop the subject."

Ralph glided in, feeling his way into the room. He congratulated Geoffrey as coolly as he would have done in the most trite circumstances. He was acting his part in his own wooden, stupid way.

"I also have had my adventures," he croaked.

"I hope the castle is all right," Ravenspur observed.

"The same idea occurred to me," Ralph went on. "One so afflicted as myself could not be of much service on the beach, so I came back to the castle. It occurred to me as possible that our enemy would take advantage of the place being deserted. So I passed the time wandering about the corridors.

"A little time ago I heard a violent commotion and screaming outside Geoffrey's room. I got to the spot as soon as possible, but when I arrived the noise had ceased. Then I stumbled over the body of a woman."

"Woman?" Ravenspur cried. "Impossible!"

"Not in the least," Ralph said coolly. "I picked her up, she was unconscious. My medical knowledge, picked up in all parts of the world, told me that the woman was suffering from some physical shock. That she was not in any danger her steady pulse showed. I placed her on the bed in the blue room."

"And there she is now?" Marion exclaimed.

"So far as I know," Ralph replied. "What she was doing here I haven't the slightest idea."

"And you don't know who she is?" Mrs. Gordon asked.

"How should I? I am blind. I should say that the woman was up to no good here; but I dare say it is possible that she has some decent excuse. On the other hand, she might be one of our deadly foes. Anyway, there she is, and there she is likely to be for some time to come."

Marion rose to her feet.

"Uncle Ralph," she said, "I feel that I could shake you. Have you no feeling?"

"We can't all have your tender heart," Ralph said meekly.

Marion ignored the compliment. She took up the decanter and poured out a glass of wine.

"I am going upstairs at once," she said. "Enemy or no enemy, the poor creature cannot be neglected. You need not come, Vera."

Vera, too, had risen to her feet. She was not going to be put aside.

"But I am coming," she said. "I will not allow you to go up those stairs alone. And Geoffrey shall accompany us."

Marion said no more. She seemed strangely anxious and restless.

Geoffrey followed with a lamp in his hands. Mrs. May lay quietly there, breathing regularly and apparently in a deep sleep.

Marion bent over the bed. As she did so she gasped and the color left her face. She fell away with a cry like fear.

"Oh," she shuddered. "Oh, it is Mrs. May!"

Vera bent over the bed. She unfastened the dress at the throat.

"What does it matter?" she said. "I know you don't like the woman, but she is suffering. Marion, where are your tender feelings?"

Marion said nothing. But she came directly to Vera's side. And Geoffrey glancing at Marion's rigid white face wondered what it all meant.

CHAPTER XLVII
TCHIGORSKY FURTHER EXPLAINS

"I don't quite follow it yet," said Geoffrey.

"And yet it is simple," Tchigorsky replied. "Here is a form of electric battery in the vault connected by tiny wires to every sleeping chamber occupied by a Ravenspur. In each of these bed-rooms a powder is deposited somewhere and the wire leads to it. At a certain time, when you are all asleep, the current is switched on, the powder destroyed without leaving the slightest trace, and in the morning you are all as dead as if you had been placed in a lethal chamber – as a matter of fact, they would have been lethal chambers.

"Almost directly, by means of the chimneys, etc., the rooms would begin to draw a fresh supply of air, and by the time you were discovered everything would be normal again. Then the battery would be removed and the wires withdrawn without even the trouble of entering the rooms to fetch them. Then exit the whole family of Ravenspur, leaving behind a greater mystery than ever. Now do you understand what it all means?"

Geoffrey nodded and shuddered.

"What do you propose to do?" he asked. "Leave the battery where it is, and – "

"Unless I am mistaken, the battery is removed already," said the Russian.

He was correct. Investigation proved that the whole thing had been spirited away.

"As I expected," Tchigorsky muttered. "Done from the vaults under the sea, doubtless. That woman's servants keep very close to her. It is wonderful how they manage to slip about without being seen. They have ascertained that an accident has happened to their mistress, and they have removed signs of the conspiracy. But for the present they cannot remove their mistress."

Tchigorsky chuckled as he spoke.

"You seem pleased over that," said Geoffrey.

"Of course I am, my boy. It enables one to do a little burglary without the chance of being found out. And you are to assist me. But I am not going to start on my errand before midnight; so till then I shall stay here and smoke. At that hour you will please join me."

"I am to accompany you, then?"

"Yes, you are going to be my confederate in crime."

Geoffrey joined the others downstairs. Delight and thankfulness were written on every face. Never had Geoffrey found his family so tender and loving.

Usually, Marion had had her feelings under control, but to-night it seemed as if she could not make enough of her cousin. She hung over him, she lingered near him, until Vera laughingly proclaimed that jealousy was rendering her desperate.

"I cannot help it," Marion said half tearfully. "I am so glad. And if you only knew – but that does not matter. I am beside myself with joy."

"I suppose that woman upstairs is all right," Ravenspur said coldly.

He was by no means pleased that Mrs. May should have intruded twice in that way. And each time there had been some accident. With so much sorrow weighing him down and with the shadow of further disaster ever haunting him, Ravenspur was naturally suspicious.

It seemed absurd, no doubt, but that woman might be taking a hand against the family fortunes. The last occasion was bad enough, but this was many times worse. In the circumstances, as he pointed out, nothing could exceed the bad taste of this intrusion into a deserted house.

"She may not have known it," Mrs. Gordon said quietly. "Who knows but that she had discovered some plot against us and had come to warn us? Perhaps the enemy divined her intentions – hence the accident."

"But was it an accident?" Geoffrey asked.

"Something mysterious, like everything that occurs to us," his wife replied. "At any rate, she is breathing regularly and quietly now, and her skin is moist and cool. Ralph said he had seen something like it in India before. He is convinced that she will be all right in the morning. Don't be angry, father."

Rupert Ravenspur constrained himself to smile.

"I will not forget what is due to my position and my hospitality, my dear," he said. "After Geoffrey's miraculous escape, after the heavy cloud of sorrow so unexpectedly raised, I cannot feel it in my heart to be angry with anybody. How did you manage to get away, Geoffrey?"

Geoffrey told his tale again. It was not nice to be compelled to invent facts in the face of an admiring family; but then the truth could not have been told without betraying Tchigorsky and blowing all his delicate schemes to the winds. He was not sorry when he had finished.

Marion wiped the tears from her eyes.

"It was Providence," she said. "Nothing more nor less."

"Little doubt of it," Gordon murmured. "Geoff, have you any suspicions?"

"I know who did it, if that is what you mean," Geoffrey said, "and so does Marion."

The girl started. Her nerves were in such a pitiable condition that any little thing set them vibrating like the strings of a rudely handled harp.

"If I did I should have spoken," she said.

"Then you have not guessed?" Geoffrey smiled. "The masts and the sculls were sawn by a girl in a blue dress and red tam-o'-shanter cap. The girl who is so like – "

He did not complete the sentence; there was something in Marion's speaking eyes that asked him not to do so. Why he could not tell; but there was nothing to be gained by what was little less than a breach of confidence.

"What does it mean, Marion?" Ravenspur asked.

"Geoffrey and I saw such a girl not long before Geoff set out on his eventful voyage," Marion explained quietly. All the fear had gone out of her eyes; she met the gaze of the speaker tranquilly. "She passed me as I was painting; I have been close to her once before. But I don't understand why Geoff is so certain that the mysterious visitor tried to drown him."

"I've no proof," Geoffrey replied. "It is merely an instinct."

As a matter of fact, he had plenty of proof. Had he not seen the girl hastening away from his boat? Had he not seen her return after the boat had been beached and mourn over the wreck like some creature suffering from deep remorse?

But of this he could say nothing. To speak of it would be to betray the fact that Tchigorsky was still alive and active in pursuit of the foe.

"That woman can be found," Ravenspur said sternly.

"I doubt it," said Geoffrey. "She has a way of disappearing that is remarkable. You see her one moment and the next she has vanished. But I am certain that she is at the bottom of the mischief."

And Geoffrey refused to say more. As a matter of fact, nobody seemed to care to hear anything further. They were worn out with anxiety and exertion. They had had little food that day; the weary hours on the beach had exhausted them.

"For the present we can rest and be thankful," Ravenspur said as he rose to go. "We can sleep with easy minds to-night."

They moved off after him, all but Geoffrey and Vera. Mrs. Gordon could still be heard moving about one of the drawing rooms. Marion had slipped off unobserved. She hardly felt equal to bidding Geoffrey good-night. The tender smile was still on her face as she crept upstairs.

Then when she reached her room it faded away. She flung herself across the bed and burst into a passionate fit of weeping. And then gradually she sobbed herself into a heavy yet uneasy slumber.

"Well, I suppose I must go, too?" Vera said, tired out, yet reluctant to leave her lover. "Tell me what it means, Geoff?"

"Have I not already explained to you, darling?"

"Yes, but I don't believe one word of it," Vera replied. A kiss sufficed to wash the bitterness of the candor away. "I don't believe you were picked up by a yacht. I don't believe that you were in any danger. I don't understand it."

"Then we are both in the same state of benighted ignorance," Geoffrey smiled. "You are right not to believe me, dearest, but I had to tell the story and I had to play a part. It is all in the desperate game we are playing against our secret foe. For the present I am a puppet in the hands of abler men than myself. What I am doing will go far to set us free later."

Vera sighed gently. She sidled closer to her lover. Mrs. Gordon was coming out of the drawing room, a sign that Vera would have to go.

"I feel that I don't want to part with you again," she whispered, her eyes looking into his and her arm about him. "I feel as if I had nearly lost you. And if I did lose you, darling, what would become of me?"

Geoffrey kissed the quivering lips tenderly.

"Have no fear, sweetheart," he said; "all is coming right. See how those people have been frustrated over and over again. They have come with schemes worthy of Satan himself and yet they have failed. And it has been so arranged that those failures seem to be the result of vexatious accident. But they are not. And they will fail again and again until the net is around them and we shall be free. Darling, you are to sleep in peace to-night."

With a last fond embrace Vera slipped from her lover's side. She smiled at him brightly from the doorway and was gone. Geoffrey lighted a cigarette that presently dropped from his fingers and his head fell forward.

He started suddenly; the cigarette smelt pungently as it singed the carpet. Somebody was whispering his name; somebody was calling him from the stairs. Then he recognized Ralph's croaking voice.

"Tchigorsky," he muttered sleepily. "I had forgotten that Tchigorsky wanted me."