"How did he get up to the room at that time of night? The Inn would be closed; the night porter of the Inn must have let him in. I must make a note of that. And what took him there? He must have had some object in view. And the room was in the set of chambers occupied by Mr. Cooper Silwood, one of the most respectable solicitors in London, and a member of the very firm of solicitors with whom Mr. Thornton transacted his business. Could it be that Mr. Thornton had gone to see Mr. Silwood about some matter? But surely not at that hour--it hardly seems possible. Still I must not neglect that phase of the case. "As regards Mr. Silwood. As he is now dead, the thing looks like leading up to a blind wall. He had been for some time away on a holiday. I must get the date when he left London. If he was in London on July 30th, or on the next day, the case would appear pretty black for him. Then there is the locked door. The door of the room in which the body was found had a special lock, and of course a special key, which Mr. Silwood carried. Some one locked the door on the dead man; the only one, presumably, who had the key to lock it was Mr. Silwood. This also looks pretty black for him. "But the motive? Suppose Silwood did kill Morris Thornton, what would be his reason? It must have been some very strong reason indeed that would make a respectable solicitor murder an important client. Most improbable--impossible, one would have said; but nothing is impossible, nothing in the world. Yet everything points to the deed having been done by Silwood. The conclusion is obvious." At this point in his reflections Gale took a turn up and down the floor. He was saying to himself, as he had said to Gilbert, that when a conclusion was obvious, then it was necessary to beware of it. His long experience had taught him that obvious conclusions rarely turned out to be correct. "Well, where are we?" Gale mused, sitting down again. "Let us say Silwood had a motive for murdering Thornton, and did actually kill him, and having committed the murder, fled the country on the pretence of taking a holiday--suppose all this; where does it land us?" Here a curious idea came into Gale's mind. He considered it doubtfully for two or three minutes; then, reminding himself of his favourite theory that nothing was impossible, he gave it tentatively a place in his thoughts. "Suppose," he said to himself, "that Silwood is not dead, and that all this palaver about the certificate of death from the Italian magistrate is a skilfully manufactured affair, a mere pretence, in fact, with the object of defeating justice? If this were so, it would complete the case with a vengeance. Still, why shouldn't Silwood be dead? Well, I must look into it, though the idea that he is alive seems rather far-fetched." Far-fetched or not, the idea fascinated the inspector as it appealed to his imagination; it haunted him so that he could not drive it out of his mind.