"When?" I asked.
"On Friday night."
"Greaves died on a Friday night," said Randall. "It is a small point, perhaps, but, like myself, the professor believes in small details."
"I suppose the agent will let me have the key," said Quarles.
"I do not know the agent. I got the key through Dr. Bates, and I can give you a card of introduction to him."
"It will be a very interesting experiment," I said, looking as learned as I could. I thought I had kept my end up very well, and far from having to pretend to be interested, as Quarles had suggested, I was profoundly interested, not in the psychological discussion, but in the Bayswater mystery. I had heard of it before, and remembered that Martin, one of the oldest members of the force, had said that it was no more a case of suicide than he was a raw recruit. I am far from saying that no mystery is to be accounted for by the supernatural, but I always want to test it in every other way first.
Quarles was pleased to jeer at me for a skeptic as we drove back to Chelsea. He did not consider me altogether a fool as a detective, but he had no use for me as a psychological student.
"Anyway, it is a pity you are undertaking this business in your present nervous state," I said. "At least let me be with you on Friday night."
"Nonsense, that would make the experiment useless. You clear up the mystery of this subtle scoundrel who has tried to get me shot and my nervous state will soon disappear."
As a matter of fact, I couldn't settle to a careful study of my recent cases, as the professor had suggested. I tried and failed. I could not forget the experiment which was to be made on Friday night, and on Wednesday morning I took action. First of all, I arranged that a special constable should be on duty in Manleigh Road, and from his appearance no one would have supposed that anything in the way of a genius had been introduced into the neighborhood. He looked a fool; he was one of the smartest men I knew. Strangely enough, on the Thursday night No. 7 was burgled quite early in the evening as soon as it was dusk. Two men got in at a basement window, and the constable was quite close at the time. He had instructions, in fact, to give warning to the burglars if there was any danger of their being seen.