“Yet you say he is affectionate?”

“Never in the world could there be so devoted a son. My life is his life. He is absorbed in what I say or do.”

Once again Holmes made a note. For some time he sat lost in thought.

“No doubt you and the boy were great comrades before this second marriage. You were thrown very close together, were you not?”

“Very much so.”

“And the boy, having so affectionate a nature, was devoted, no doubt, to the memory of his mother?”

“Most devoted.”

“He would certainly seem to be a most interesting lad. There is one other point about these assaults. Were the strange attacks upon the baby and the assaults upon your son at the same period?”

“In the first case it was so. It was as if some frenzy had seized her, and she had vented her rage upon both. In the second case it was only Jack who suffered. Mrs. Mason had no complaint to make about the baby.”

“That certainly complicates matters.”

“I don’t quite follow you, Mr. Holmes.”

“Possibly not. One forms provisional theories and waits for time or fuller knowledge to explode them. A bad habit, Mr. Ferguson, but human nature is weak. I fear that your old friend here has given an exaggerated view of my scientific methods. However, I will only say at the present stage that your problem does not appear to me to be insoluble, and that you may expect to find us at Victoria at two o’clock.”

It was evening of a dull, foggy November day when, having left our bags at the Chequers, Lamberley, we drove through the Sussex clay of a long winding lane and finally reached the isolated and ancient farmhouse in which Ferguson dwelt. It was a large, straggling building, very old in the centre, very new at the wings with towering Tudor chimneys and a lichen-spotted, high-pitched roof of Horsham slabs. The doorsteps were worn into curves, and the ancient tiles which lined the porch were marked with the rebus of a cheese and a man after the original builder. Within, the ceilings were corrugated with heavy oaken beams, and the uneven floors sagged into sharp curves. An odour of age and decay pervaded the whole crumbling building.

There was one very large central room into which Ferguson led us. Here, in a huge old-fashioned fireplace with an iron screen behind it dated 1670, there blazed and spluttered a splendid log fire.

The room, as I gazed round, was a most singular mixture of dates and of places. The half-panelled walls may well have belonged to the original yeoman farmer of the seventeenth century. They were ornamented, however, on the lower part by a line of well-chosen modern water-colours; while above, where yellow plaster took the place of oak, there was hung a fine collection of South American utensils and weapons, which had been brought, no doubt, by the Peruvian lady upstairs. Holmes rose, with that quick curiosity which sprang from his eager mind, and examined them with some care. He returned with his eyes full of thought.

“Hullo!” he cried. “Hullo!”

A spaniel had lain in a basket in the corner. It came slowly forward towards its master, walking with difficulty. Its hind legs moved irregularly and its tail was on the ground. It licked Ferguson’s hand.

“What is it, Mr. Holmes?”

“The dog. What’s the matter with it?”

“That’s what puzzled the vet. A sort of paralysis. Spinal meningitis, he thought. But it is passing. He’ll be all right soon - won’t you, Carlo?”

A shiver of assent passed through the drooping tail. The dog’s mournful eyes passed from one of us to the other. He knew that we were discussing his case.

“Did it come on suddenly?”

“In a single night.”

“How long ago?”

“It may have been four months ago.”

“Very remarkable. Very suggestive.”

“What do you see in it, Mr. Holmes?”