“The Peter Hay case was crystal clear so far as one side was concerned. It required no marvellous insight to see what had happened. It wasn't by any possibility a one-man murder. At least two men must have been on the spot to overpower Peter and tie him up. They—or at least one of them—was a better-class fellow, or Peter Hay would have been in his shirt-sleeves instead of having his jacket on. And the jacket implied that he knew they were coming that evening, too. Further, the fact that they had amyl nitrite ready in their pockets is enough to prove two things. They weren't casual strangers, for they knew about his liability to cerebral congestion. And they premeditated killing him in certain circumstances. We worked out pretty definitely the course of events which led to his death, so I needn't go over that again. I suppose we were right in the main points, inspector?” Armadale, primed with the information he had extracted from Aird, was able to confirm this. “They used surgical bandages because they hoped to leave no marks on the skin, I suppose?” Sir Clinton inquired. “That was the idea, Aird admitted, sir. He thought they'd succeeded, and he was surprised to find they'd made a mess of it.” Sir Clinton smiled, apparently at the thought of Aird's discomfiture. “Well, if they bungled one side of the affair, they certainly managed to leave us in the dark about the second side: the motive behind the murder. It wasn't robbery, obviously. It wasn't bad feeling—everyone we examined had a good word for Peter Hay. It couldn't be homicidal mania—not with two of them mixed up in it. That left, so far as I could see, only one probable motive at the back of the thing. Either they wanted to force Peter Hay into something he didn't like, or else he knew something about them which they were afraid of. “Peter Hay wasn't the blackmailing type, from all we learned about him. That notion wouldn't hold water for a moment. So, if he had to be silenced, then the information he had must have been something he'd come across quite innocently. What it was I couldn't guess. In fact, the whole idea was very vague in my mind, since there didn't seem anything definite to support it. That was the stage I'd reached when we sat in the garden and discussed the thing. “But there was one thing that seemed to lead on to something fresh—the silver we found in Peter Hay's drawer. That silver was the murderers' mistake—the silly thing that gives them away. No sensible person would ever have tried to throw a suspicion of breach of trust on Peter Hay. The thing was absurd on the face of it, from what we learned of his character. But these fellows weren't looking at it objectively. They would have abused their trust in Hay's shoes; and naturally they saw nothing _outré_ in faking a petty theft and trying to throw it on his shoulders. That made me think.