"Perfectly."
"She spoke of her uncle's sensitiveness to noises; she had on one or two occasions surprised him in a listening attitude. That gave me a clew. What was he listening for? Mr. Ratcliffe had only given way to this listening attitude recently; in fact, only since his return from his last voyage. It would seem that since his return his mental balance had become unstable. There was some constant irritation in his brain which brought fear, and in his dead eyes there was terror. My theory was complete; I had only to fit the facts into it. I suppose, Mr. Wigan, you have found out all about the people living on either side of Ratcliffe's house?"
"Both are families above suspicion," I answered. "I also tried Ossery Road, the gardens of which run down to those on that side of Blenheim Square. The house immediately behind No. 12 is occupied by a doctor."
"I know. I called upon him recently to put some scientific point to him," said Quarles with a smile. "I came to the conclusion that he could give me no information about Mr. Ratcliffe. Rather curiously, he did not like Mr. Ratcliffe."
"So I discovered," I answered, and I was conscious of resenting the professor's active interference in the case. There is no telling what damage an amateur may do.
"His dislike was a solid fact," said Quarles. "I congratulate you on not being put on a false scent by it. Many detectives would have been. The gardens end on to each other—a doctor, a knowledge of subtle poisons—oh, there were materials for an excellent case ready to hand."
"We are getting away from the point, professor," I said, somewhat tartly.
"No, I am coming to it. I concentrated my attention on the house two doors further down the road. It would not be difficult to creep along the garden wall even in the dark. Two Chinese gentlemen boarded there, I was told. No one had noticed them very particularly in the neighborhood. There are several boarding-houses in Ossery Road, and many foreigners over here for study or upon business go to live in them. I called, but the Chinese gentlemen were visiting in the country, and were not expected back for another fortnight. As a fact, they were not Chinamen at all, but Tibetans, and I do not fancy they will come back."
"Tibetans. How do you know? You did not see them?"
"No, it is a guess; because on his last journey Mr. Ratcliffe wandered in Tibet. I have correspondents in Northern India, and it was not very difficult to get this information by cable. You do not know Tibet, Mr. Wigan?"