He entered as coolly and easily as if he had been doing this kind of thing all his life, as if he had the full use of his eyesight.

"I can't see you, but, of course, you are there," he said. "Tchigorsky sent me because he cannot come himself. The jade he calls his mistress has need of him. Muffle yourself and follow me. Not too closely."

Geoffrey was only too glad of the opportunity. He passed under the shadow of the rocks until he gained the path to the head of the cliffs and here Ralph paused.

"We are safe now," he said. "You can remove your disguise and cross the terrace. There is not a living soul in the castle at present."

"All the servants are on the beach, then?"

"Every one of them, both male and female, which is a flattering testimony to your popularity, Geoffrey. I opine that they will be pleased to see you in the morning. By the way, have you concocted a plausible story to account for your escape?"

"I haven't," Geoffrey admitted with a smile. "I preferred to leave it to the greater talents of Tchigorsky and yourself. I have no genius for fiction."

Ralph muttered that the matter might be safely left in their hands, and then they entered the deserted castle and made their way to Ralph's room. Here the two doors were closed and Ralph sat down silently over his pipe.

"Is anything going to happen?" Geoffrey asked.

"A great deal during the next hour or two," Ralph replied. "But it is impossible to forecast, and you will see it all for yourself in good time. I can't do anything until I have heard further from our friend Tchigorsky."

Half an hour passed in dead silence, and then there was a rapping on the window. When the casement was thrown open, the head of Tchigorsky appeared. He was clad in Oriental robes and had made his way upwards by climbing the thick ivy that grew on that side of the house. He nodded to Geoffrey.

"I told you we should meet again," he said. "I have just ten minutes to spare. A cigarette, please."

Geoffrey handed over the cigarette. "Have you discovered it all?" Ralph asked.

"I have discovered nothing," Tchigorsky said calmly from behind the cloud of smoke. "At present I have not the remotest idea which way she will strike."

"Ah, she is in one of her suspicious moods."

"When she trusts nobody. Quite right. All I can tell you is that she is coming here presently. She is well aware that there is not a soul in the house. She knows that this state of things is likely to last for some time. She will come by and by, and with her she will bring some great danger to the house of Ravenspur. What form that danger is to take I cannot say. But I shall find out."

The last words came from Tchigorsky's lips with a snap.

"But she will want confederates," said Geoffrey.

"She may or she may not. She is a woman of infinite resource. Nobody knows what mischief she is capable of. If she brings me along, I may be exceedingly useful; if she leaves me behind I shall be more usefully employed in going over her papers and documents. You see, I know the language. But, be that as it may, this is going to be an eventful night."

Tchigorsky finished his cigarette and rose to go. He had few instructions to leave behind him, and these few were of an exceedingly simple nature. All that Geoffrey and Ralph Ravenspur had to do was to watch. They were to keep their eyes open and be largely guided by events. And there were to be no lights.

Half an hour passed before Ralph rose and softly opened the door. For a little time he threw the casement open wide. As Geoffrey drew a match from his box Ralph laid a restraining hand on his arm.

"No more smoking," he said. "I purposely opened the casement to sweeten the air of the room. My dear boy, you do not want to betray us with the smell of fresh tobacco. The enemy would take alarm at once."

"I had forgotten," Geoffrey murmured. "How stupid of me!"

Again silence and painful tension on the nerves. Presently below came the soft fall of a foot, and then a noise as if a human body had come in contact with some object in the dark. There was the scratch of a match, and a ball of flame flickered in ghastly fashion in the hall.

"The foe is here," Ralph whispered. "Go and look over. Your rubber-soled boots are in the corner. Put them on."

Geoffrey did as he desired. He crept along the corridor until he could look down into the hall. There he saw a woman—a woman who wore short skirts and a closely fitting jacket. She had a small lantern in her hand, the light of which she seemed to lower or heighten by pressing a stud.

Behind her came the two Orientals, who carried a small but heavy brass-bound box between them. This, at a sign from the woman, they deposited on the floor.

As far as Geoffrey could judge neither of these men was Tchigorsky. He could catch the sound of whispered conversation, but the words conveyed no meaning to his ears. The two discoursed in a language he did not understand.

A hand was laid on Geoffrey's arm. He turned to see Ralph by his side. The latter bent over the balustrade listening with all his ears. Down below the brass box was being opened and the contents were placed upon the floor.

The contents looked like machinery, but it was machinery of a kind that Geoffrey had never seen before. There was a small disk of hammered copper, and to this was attached a number of what seemed to be india-rubber snakes. At a sign from the woman the two Asiatics picked up the box and its contents and started away toward the kitchen.

Noiseless as they were, Ralph heard them. He clutched his companion's arm.

"They have gone," he whispered. "In which direction?"

"They had moved off towards the kitchen," said Geoffrey.

"Good! This thing is turning out exactly as I expected. They had something with them?"

"Yes, a thing like a copper octopus with india-rubber tentacles. They have taken it with them. A most extraordinary affair."

"It will be more extraordinary still before it is finished," Ralph said grimly. "Follow them and report what you see. Take good care not to be seen. Unless I am mistaken they are going down to the vaults and are planning a coup to do for us all to-night."

Geoffrey crept silently down the stairs. Then he made his way swiftly along the passages until he came to the cellars. Then the steady blowing of a current of fresh air told him that Ralph's suggestion was right. Down he went until he came to the channel leading to the vaults.

But he was cautious. He peeped down. Below him were three figures, and once more they had spread out their queer apparatus. By the side of it were two large glass-stoppered bottles, such as one sees in a laboratory, receptacles for acids and the like. They were tightly tied over the stoppers.

The woman picked up one of them and removed the parchment. Before she drew the stopper she donned thick glasses and a mask for her face, the two Orientals doing the same. They were evidently dealing with some very dangerous poison.

The stopper was removed and a few spots of the acid dropped on the copper disc. A white smoke arose, which, small as it was, filled the air with a pungent odor. Almost immediately the acid was wiped off and the odor ceased. Only just a whiff of it reached Geoffrey's nose, but it turned him faint—giddy for an instant.

What was going to happen next?