“Well, it begins to define itself. I have been to the house-agent’s. Our client, as he told us, has been there five years. It was unlet for a year before then. The previous tenant was a gentleman at large named Waldron. Waldron’s appearance was well remembered at the office. He had suddenly vanished and nothing more been heard of him. He was a tall, bearded man with very dark features. Now, Prescott, the man whom Killer Evans had shot, was, according to Scotland Yard, a tall, dark man with a beard. As a working hypothesis, I think we may take it that Prescott, the American criminal, used to live in the very room which our innocent friend now devotes to his museum. So at last we get a link, you see.”

“And the next link?”

“Well, we must go now and look for that.”

He took a revolver from the drawer and handed it to me.

“I have my old favourite with me. If our Wild West friend tries to live up to his nickname, we must be ready for him. I’ll give you an hour for a siesta, Watson, and then I think it will be time for our Ryder Street adventure.”

It was just four o’clock when we reached the curious apartment of Nathan Garrideb. Mrs. Saunders, the caretaker, was about to leave, but she had no hesitation in admitting us, for the door shut with a spring lock, and Holmes promised to see that all was safe before we left. Shortly afterwards the outer door closed, her bonnet passed the bow window, and we knew that we were alone in the lower floor of the house. Holmes made a rapid examination of the premises. There was one cupboard in a dark corner which stood out a little from the wall. It was behind this that we eventually crouched while Holmes in a whisper outlined his intentions.

“He wanted to get our amiable friend out of his room - that is very clear, and, as the collector never went out, it took some planning to do it. The whole of this Garrideb invention was apparently for no other end. I must say, Watson, that there is a certain devilish ingenuity about it, even if the queer name of the tenant did give him an opening which he could hardly have expected. He wove his plot with remarkable cunning.”

“But what did he want?”

“Well, that is what we are here to find out. It has nothing whatever to do with our client, so far as I can read the situation. It is something connected with the man he murdered - the man who may have been his confederate in crime. There is some guilty secret in the room. That is how I read it. At first I thought our friend might have something in his collection more valuable than he knew - something worth the attention of a big criminal. But the fact that Rodger Prescott of evil memory inhabited these rooms points to some deeper reason. Well, Watson, we can but possess our souls in patience and see what the hour may bring.”

That hour was not long in striking. We crouched closer in the shadow as we heard the outer door open and shut. Then came the sharp, metallic snap of a key, and the American was in the room. He closed the door softly behind him, took a sharp glance around him to see that all was safe, threw off his overcoat, and walked up to the central table with the brisk manner of one who knows exactly what he has to do and how to do it. He pushed the table to one side, tore up the square of carpet on which it rested, rolled it completely back, and then, drawing a jemmy from his inside pocket, he knelt down and worked vigorously upon the floor. Presently we heard the sound of sliding boards, and an instant later a square had opened in the planks. Killer Evans struck a match, lit a stump of candle, and vanished from our view.