"You showed me the only way to close that lock from the outside. There was no hole in the glass, so there must be in the sash. It was not visible—you had been all over it, and a man of your profession isn't a totally untrained observer—so the hole was plugged. I hadn't seen the plug, so it was concealed by paint—"
I was trying to work a toothpick through the plughole. She offered me a wire hairpin, straightened out, and with it I pushed the hasp into place from outside, saw the lever snap in to hold it fast. I had worked the catch as Clayte had worked it—from outside.
"How did you know it was this window?" I asked, forced to agree that she had guessed right as to the sash lock. "There are two more here, either of which—"
"No, please, Mr. Boyne. Look at the angle of the roof that cuts from view any one climbing from this window—not from the others."
We were all leaning in the window now, sticking our heads out, looking down, looking up.
"I can't yet see how you get the rope and hook," I said. "Still seems to me that an outside man posted on the roof to help in the getaway is more likely."
"Maybe. I can't deal with things that are merely likely. It has to be a fact—or nothing—for my use. I know that there wasn't any second man because of the nicks Clayte's grappling hook has left in the cornice up there."
"Nicks!" I said, and stood like a bound boy at a husking, without a word to say for myself. Of course, in this impasse of the locked windows, my men and I had had some excuse for our superficial examination of the roof. Yet that she should have seen what we had passed over—seen it out of the corner of her eye, and be laughing at me—was rather a dose to swallow. She'd got her hair and her hat and veil to her liking, and she prompted us,
"So now you want to get right down stairs—don't you—and go up through that other building to its roof?"
I stared. She had my plan almost before I had made it.