“I can conceive of no explanation.”
“And yet there should be no combination of events for which the wit of man cannot conceive an explanation. Simply as a mental exercise, without any assertion that it is true, let me indicate a possible line of thought. It is, I admit, mere imagination; but how often is imagination the mother of truth?
“We will suppose that there was a guilty secret, a really shameful secret in the life of this man Douglas. This leads to his murder by someone who is, we will suppose, an avenger, someone from outside. This avenger, for some reason which I confess I am still at a loss to explain, took the dead man’s wedding ring. The vendetta might conceivably date back to the man’s first marriage, and the ring be taken for some such reason.
“Before this avenger got away, Barker and the wife had reached the room. The assassin convinced them that any attempt to arrest him would lead to the publication of some hideous scandal. They were converted to this idea, and preferred to let him go. For this purpose they probably lowered the bridge, which can be done quite noiselessly, and then raised it again. He made his escape, and for some reason thought that he could do so more safely on foot than on the bicycle. He therefore left his machine where it would not be discovered until he had got safely away. So far we are within the bounds of possibility, are we not?”
“Well, it is possible, no doubt,” said I, with some reserve.
“We have to remember, Watson, that whatever occurred is certainly something very extraordinary. Well, now, to continue our supposititious case, the couple—not necessarily a guilty couple—realize after the