“Were there many of them, then?” “I understand that Stanworth’s practice was a fairly extensive one,” Roger replied ironically. “Anyhow, I was able to narrow down the field to a certain extent. Then I began to go over once more the evidence we had collected. The question I kept asking myself was—is there a single item that gives a definite pointer towards any certain person, male or female?” “Female?” Roger repeated surprisedly. “Certainly. In spite of everything—the footprint in the flower bed, for example—I was still keeping before me the possibility of a woman being mixed up in it. It didn’t seem altogether probable, but I couldn’t afford to lose sight of the bare possibility. And it’s lucky I did, for it was just that which finally put me on the right track.” “Good Lord!” “Yes; I admit I was slow in the up-take, for the fact had been staring me in the face the whole time, and I never spotted it. You see, the key to the whole mystery was that there was a _second_ woman in the library that night.” “How on earth do you know that?” Alec asked in consternation. “By the hair we found on the settee. I put it away in the envelope, you remember, and promptly forgot all about it, assuming it to have been one of Mrs. Plant’s. It struck me suddenly in the garden just now that it wasn’t anything of the sort; Mrs. Plant’s hair is very much darker. Of course that opened up an entirely new field for speculation.” “Good Lord!” “Yes, it is rather surprising, isn’t it?” Roger continued equably. “That set my brain galloping away like wildfire, I need hardly tell you; and five minutes later the whole thing became absolutely plain to me. I’m a little hazy about some of the details, of course, but the broad lines are clear enough.” “You mean you guessed who the second woman was?” “Hardly guessed. I knew at once who she must be.” “Who?” Alec asked, with unconcealed eagerness. “Wait a bit. I’m coming to that. Well, then I began to put two and two together. I’d got a pretty shrewd idea already of the personal appearance of the man himself.” “Oh, it was a man then?” “Yes, it was a man right enough. There was never any doubt that a man must have done the actual killing. No woman would have been strong enough for the struggle that must have taken place. Stanworth was no weakling, so that gives us the fact that the man must have been a strong, burly sort of person. From the footprint and the length of those strides across the bed he was evidently both tall and largely built; from the clever way in which everything was left he must have been possessed of a fund of cunning; from the manner in which he left that window fastened behind him it was clear that he was thoroughly accustomed to handling lattice windows. Well, what does all that give us? It looked obvious to me.” Alec was staring intently at the speaker, following every word with eager attention. “I think I see what you’re getting at,” he said slowly.