He investigated, and found, hanging from a crevice in the rough edge of the sill, a woman’s hair. It was a long hair, and jet black.

“That explains the closeness of those finger-marks,” he muttered. “A woman in the case, eh? Now, why was she here, in front of the closed window? And was she here last night? Or this morning, quite innocent like? The odds are it was last night. One doesn’t crouch outside a Cabinet Minister’s window in daylight. Nor at all, unless one’s up to no good. No, I think you were here last night, my black beauty. I love little pussy, her hair is so black, and if I don’t catch her she’ll never come back. Now where did you come from, Blackie dear? And have you left any other cards? O, Shades of Doyle! What a game!”

He stepped back on to the path and knelt to examine the stone edging to the flower-bed. In the position she must have been in, the woman would most probably, he argued, have been on one knee and had the foot of the other leg pressed vertically against this edging.

She had; but Anthony was doubly surprised at what he found. For why, in this dry weather, should the mark of her foot be there at all? And, as it was there, why should it look like a finger-print a hundred times enlarged?

He scratched his head. This was indeed a crazy business. Perhaps he was off the rails. Still, he’d better go on. This all might have something to do with the case.

More closely he examined this footprint that was like a finger-print. Now he understood. The mark had remained because the peculiar sole of this peculiar shoe had been wet and earthy. There had been no rain for a week. Why was the shoe wet? And why—he looked carefully about—were there no other such marks on the flagstones of the path? Ah, yes; that would be because in ordinary walking or running the peculiar shoes did not press hard enough to leave anything but a wet patch which would quickly dry. Whereas, in pressing the sole of the foot against that edging to the flower-bed, much more force would have to be used to retain balance—sufficient force to squeeze wet clayish earth out in a pattern from that peculiar sole.

But what about the wetness? He hadn’t settled that. Suddenly his mind connected the peculiarity of that imprint with the idea of water. A rope-soled sandal. When used? Why, bathing. Here Anthony laughed aloud. “Sleuth, you surpass yourself!” he murmured. “Minister murdered by Bathing Belle—only not at the seaside! Cock Robin’s murderer not Sparrow as at first believed, but one W. Wagtail! Gethryn, you’re fatuous. Take to crochet.”

He started for the verandah door. Half-way he stopped, suddenly. He’d forgotten the river. But the idea was ridiculous. But, after all—well, he’d spend ten minutes on it, anyhow. Now, to begin—assuming that the woman had come out of the river and had wanted (strange creature!) to get back there—he would work out her most probable route and follow it. If within five minutes he had found no more signs of her, he’d stop.

After a moment’s calculation he started off, going through the opening in the yew hedge, down the grass bank to his right and then crossing the rose garden at whose far side there began a pergola.

At the entrance to the pergola he found, caught round a thorny stem of the rose-creeper that fell from the first cross-piece of the archway, four long black hairs.