‘Come, Arthur,’ said Settle cheerfully. ‘Miss Patterson and a friend of mine have come to see you.’

But the young fellow in the window seat only blinked. Yet a moment or two later I saw him watching us again—furtively and secretly.

‘Want your tea?’ asked Settle, still loudly and cheerfully, as though talking to a child.

He set on the table a cup full of milk. I lifted my eyebrows in surprise, and Settle smiled.

‘Funny thing,’ he said, ‘the only drink he’ll touch is milk.’

In a moment or two, without undue haste, Sir Arthur uncoiled himself, limb by limb, from his huddled position, and walked slowly over to the table. I recognized suddenly that his movements were absolutely silent, his feet made no sound as they trod. Just as he reached the table he gave a tremendous stretch, poised on one leg forward, the other stretching out behind him. He prolonged this exercise to its utmost extent, and then yawned. Never have I seen such a yawn! It seemed to swallow up his entire face.

He now turned his attention to the milk, bending down to the table until his lips touched the fluid.

Settle answered my inquiring look.

‘Won’t make use of his hands at all. Seems to have returned to a primitive state. Odd, isn’t it?’

I felt Phyllis Patterson shrink against me a little, and I laid my hand soothingly on her arm.

The milk was finished at last, and Arthur Carmichael stretched himself once more, and then with the same quiet noiseless footsteps he regained the window seat, where he sat, huddled up as before, blinking at us.

Miss Patterson drew us out into the corridor. She was trembling all over.

‘Oh! Dr Carstairs,’ she cried. ‘It isn’t him—that thing in there isn’t Arthur! I should feel—I should know—’

I shook my head sadly.

‘The brain can play strange tricks, Miss Patterson.’

I confess that I was puzzled by the case. It presented unusual features. Though I had never seen young Carmichael before there was something about his peculiar manner of walking, and the way he blinked, that reminded me of someone or something that I could not quite place.

Our dinner that night was a quiet affair, the burden of conversation being sustained by Lady Carmichael and myself. When the ladies had withdrawn Settle asked me my impression of my hostess.

‘I must confess,’ I said, ‘that for no cause or reason I dislike her intensely. You are quite right, she has Eastern blood, and, I should say, possesses marked occult powers. She is a woman of extraordinary magnetic force.’

Settle seemed on the point of saying something, but checked himself and merely remarked after a minute or two: ‘She is absolutely devoted to her little son.’

We sat in the green drawing-room again after dinner. We had just finished coffee and were conversing rather stiffly on the topics of the day when the cat began to miaow piteously for admission outside the door. No one took any notice, and, as I am fond of animals, after a moment or two I rose.