“But what harm can there be in that?”

“Well, there is at least a curious coincidence of dates.  A ventilator is made, a cord is hung, and a lady who sleeps in the bed dies.  Does not that strike you?”

“I cannot as yet see any connection.”

“Did you observe anything very peculiar about that bed?”

“No.”

“It was clamped to the floor.  Did you ever see a bed fastened like that before?”

“I cannot say that I have.”

“The lady could not move her bed.  It must always be in the same relative position to the ventilator and to the rope—­or so we may call it, since it was clearly never meant for a bell-pull.”

“Holmes,” I cried, “I seem to see dimly what you are hinting at.  We are only just in time to prevent some subtle and horrible crime.”

“Subtle enough and horrible enough.  When a doctor does go wrong he is the first of criminals.  He has nerve and he has knowledge.  Palmer and Pritchard were among the heads of their profession.  This man strikes even deeper, but I think, Watson, that we shall be able to strike deeper still.  But we shall have horrors enough before the night is over; for goodness’ sake let us have a quiet pipe and turn our minds for a few hours to something more cheerful.”

About nine o’clock the light among the trees was extinguished, and all was dark in the direction of the Manor House.  Two hours passed slowly away, and then, suddenly, just at the stroke of eleven, a single bright light shone out right in front of us.

“That is our signal,” said Holmes, springing to his feet; “it comes from the middle window.”

As we passed out he exchanged a few words with the landlord, explaining that we were going on a late visit to an acquaintance, and that it was possible that we might spend the night there.  A moment later we were out on the dark road, a chill wind blowing in our faces, and one yellow light twinkling in front of us through the gloom to guide us on our sombre errand.

There was little difficulty in entering the grounds, for unrepaired breaches gaped in the old park wall.  Making our way among the trees, we reached the lawn, crossed it, and were about to enter through the window when out from a clump of laurel bushes there darted what seemed to be a hideous and distorted child, who threw itself upon the grass with writhing limbs and then ran swiftly across the lawn into the darkness.

“My God!” I whispered; “did you see it?”

Holmes was for the moment as startled as I. His hand closed like a vice upon my wrist in his agitation.  Then he broke into a low laugh and put his lips to my ear.

“It is a nice household,” he murmured.  “That is the baboon.”

I had forgotten the strange pets which the doctor affected.  There was a cheetah, too; perhaps we might find it upon our shoulders at any moment.  I confess that I felt easier in my mind when, after following Holmes’ example and slipping off my shoes, I found myself inside the bedroom.  My companion noiselessly closed the shutters, moved the lamp onto the table, and cast his eyes round the room.  All was as we had seen it in the daytime.  Then creeping up to me and making a trumpet of his hand, he whispered into my ear again so gently that it was all that I could do to distinguish the words: