There, scored in the sand, was a deep furrow, reaching to within a foot of the waves, where it stopped as if it had been wiped out from a slate with a damp sponge. Gimblet had no doubt what it was. A boat had been beached here, and that lately. A glance at the stones surrounding the bay showed him that the water was falling, for in quiet little pools, within the outer breakwater of rocks, a damp line showed on the granite a full quarter of an inch above the water. By a rapid calculation of the time it would take for that watermark to dry, the detective was able to form some idea of the rate at which the loch was falling, and he thought he could judge the slope of the beach sufficiently well to calculate about how long it was since the track in the sand had reached to the brink of the waves. It was a rough guess, but, if he were right, then a boat had landed in that bay some forty-two hours ago. But there were other traces, besides, the tracks of him who had brought the boat ashore. From where Gimblet stood, a double row of footprints, going and returning, showed plainly between the water and the stones to which the sand quickly gave place. They were the tracks left by large boots with singularly pointed toes, and with no nails on the soles. Emphatically not boots such as any of the men of those parts would be likely to wear. Gimblet bent over the sand. When he rose once more and stood erect upon the beach, he saw under the shadow of the pines the figure of a tall thin man with a lean face and straggling reddish moustache, who was watching him with an eye plainly suspicious. He was dressed in knickerbockers and coat of rough tweed of a large checked pattern, and carried a spy-glass slung over his back. The detective went to him at once. "Are you employed on the Inverashiel estate?" he asked civilly. "I'm Duncan McGregor, his lordship's head keeper," was the reply, given in the cold tones of one accosted by an intruder. Gimblet hastened to introduce himself and to explain his presence, and McGregor condescended to thaw. "I should be very much obliged," said Gimblet, "if you would take a look at the sands where you saw me standing. I'd like to know your opinion on some marks that are there." The keeper strode down to the beach. "A boat will have been here," he pronounced after a rapid scrutiny. "Lately?" asked Gimblet. He saw the man's eyes go, as his own had done, to the watermarks on the rocks. "No sae vary long ago," he said, "I'm thinkin' it will hae been the nicht before lairst that she came here." "Ah," said Gimblet, "I'm glad you agree with me. That's what I thought myself. Do boats often come ashore on this beach?" McGregor considered.