“Yes-yes-I think it does. And, Lydia, you said this was to be the last job.”

“Of course. Only don’t worry. It’s not good for you.”

He said, “No, it isn’t. Sometimes-I do-feel ill-”

Her hand came down on his shoulder and pressed it.

“Just go off to bed and leave everything to me. All you’ve got to think about is your spiders.”

On the other side of the panel Miss Silver had been moving inch by inch. The passage went on past the opening to the study. It would be interesting to know where it came out, but this was neither the time nor the place for anything which did not bear directly upon the present emergency. Craig followed her, she moved to leave the way clear for Miss Crewe’s retreat. They had indeed no more than a bare margin of safety when the panel slid and a rectangle of light lay on the passage floor. If Lydia Crewe had looked to her right she might have seen them. She held an electric torch. If she had turned it in their direction she must have done so. She looked neither to right nor left. As Henry shut the panel behind her, she followed the beam of the torch along the passage by the way that she had come.

When all sound of her going had died away Craig bent to Miss Silver’s ear.

“Well, what do we do next?”

She answered him, not in words but by a light pressure upon his arm, in obedience to which he began to move before her down the passage. But when they came to the door by which they had entered they found it locked against them. Craig allowed himself an almost noiseless laugh.

“Well-what now? I suppose we go back and see where the other end comes out. Have you any idea of where that may be? You know the geography of the house, and I don’t.”

She said in her usual composed manner,

“It would be in the hall or in the drawing-room, I should think. Both have panelling of a character very similar to that of the study.”

They retraced their steps. As they approached the panel which had been ajar, it was momentarily startling to see that light still came from it. Henry Cunningham had closed it-they had heard the click of the spring from where they stood, a yard or two away on the other side. But almost as Craig touched Miss Silver in a warning gesture they could both see that the light now came, not from the edge of the panel, but from a round knothole some five foot up from the floor. There was no doubt about its purpose. Anyone who approached through the passage could make sure that the coast was clear before stepping into the room.

Miss Silver had to raise herself a little in order to make this peephole available. She had a good view of the writing-table, and of Henry Cunningham leaning over it. In front of him on a sheet of white paper lay the spider which he had been dissecting, a sight which she found repulsive in the extreme. In his right hand he held a pair of tweezers with which with meticulous care he was inserting a large red stone into the cavity which had been made in the spider’s body. She could not doubt for a moment that she was looking at one of Lady Melbury’s lost rubies-probably, from its size, the central stone of her diamond and ruby necklace. It disappeared into the body of the spider and the tweezers were laid down. Another small instrument was then dipped into a saucer in which there was something black and glutinous, and drop by drop the stone was covered and the body rounded out again. Henry Cunningham’s hand was steady, his absorption complete.

After a minute Miss Silver yielded her place to Craig. Both received the same impression. For this time at least, Henry Cunningham was in a world of his own. It was a world in which he was hampered by neither doubt nor efficiency, a world in which there was no moral law and therefore no crime. There was only his own skill and the means of exercising it. The moment in which the thought of Maggie Bell had troubled him, the moment in which he had said of Lucy Cunningham, “She is my sister,” belonged to a different world altogether, and it was one from which he shrank, and from which he must at any cost escape.

Miss Silver began to move forward along the passage. It came out, as she supposed it might, in one of the darker corners of the hall, and the panel slid as silently as the other had done. Lydia Crewe would have seen to that. There was still a light burning. It striped the darkness as the panel slid back, seeming much brighter than it really was. The pressure of Craig’s hand upon the wood stopped suddenly. The dining-room light clicked out and Nicholas Cunningham came into view. The gap in the panel showed his easy, confident air. He crossed the hall and went soft-foot up the stairs. A door opened and shut on the landing above.

Miss Silver suggested that they should leave by way of the back door. In Miss Cunningham’s probable state of mind she would not be able to recall with any certainty whether she had ever locked it. Besides, by the time she came to consider the matter at all too many other things would have happened for it to be of any importance.

They came out on to the paved yard and by way of a gravelled path to a garden gate. As Craig closed it behind him, the church clock gave four warning strokes to announce the hour, and then struck one. The night air was cool and soft. After the dusty passage and the airless shut-in feeling of the kitchen and scullery it had a living quality. Craig filled his lungs with it. To creep by stealth through another man’s house in the middle of the night was not an experience that he had enjoyed, or one that he would wish to repeat. And where was it going to land them? That was what he wanted to know! As far as he could make out they were very comfortably situated between the devil and the deep sea. If Miss Silver made tracks for a telephone and informed Frank Abbott or the county police that she had located the Melbury rubies, the balloon was bound to go up. That wouldn’t have mattered if Lydia Crewe wasn’t bound to go up with it, in which case he could see that he was going to have trouble with Rosamond, who was practically certain to say that she couldn’t marry him tomorrow. No, not tomorrow-tomorrow had already become today. It had become his wedding day, and he saw Rosamond slipping away from him into some damned nonsensical Cloud-cuckoo-land where she wouldn’t marry him at all. If he could only get Miss Silver to hold her hand until after half past ten, as far as he was concerned she could go ahead and have the whole lot of them arrested.

They walked, and the light moving air went with them. He said,

“What are you going to do?”

She stopped and turned to face him.

“I do not know. I think we must go back.”

“Into the house?”

“No-that should not be necessary. But I am not easy about Miss Cunningham. I believe that her life is in danger.”

“Her life!”

“Mr. Lester, you heard the conversation between Miss Crewe and Mr. Cunningham. Did it leave you in any doubt as to her intentions with regard to his sister?”

“I suppose not. It seems incredible all the same.”

She said soberly,

“Murder must always seem incredible to the normal mind. The murderer has lost his balance. His own desires, his own plans, his own safety have come to outweigh normal control and the moral law. With each further step he becomes more justified in his own eyes, more inflated with his own importance, and more certain that he can carry out his plans with success. This would not be Miss Crewe’s first step into crime. Whether or not she took a personal part in the removal of Maggie Bell and the death of Miss Holiday, I have not the slightest doubt that she was cognizant of both those murders. We may never know just what happened to Maggie, but working as she did at the Dower House, it seems probable that she saw something which might have been dangerous if she were given time to put two and two together and think about the result. It is quite certain that this is what happened in the case of Miss Holiday. In Miss Crewe’s absence, she went prying into her room. Surprised by Mrs. Bolder, she pushed a chance-come envelope into her overall pocket. As Miss Crewe herself suggested, it had probably slipped down between the seat and the side of a chair. The whole thing was due to no more than idle curiosity and to the instinctive movements of a maid who is tidying a room. She would shake up the cushions and run her hand round the side of any chair which had been occupied. But you know what that envelope contained-a sketch of Lady Melbury’s diamond and ruby necklace. The first sketch in fact from which a copy was to be prepared.”