“What do you make of it, Mr. Cargill?” he inquired, after a moment or two. “I haven't thought much about it,” Cargill answered. “It seems straightforward enough. Somebody must have been behind the groyne and fired a shot. It's within easy shooting distance of the rock where the body was found.” Wendover opened his mouth as if to say something. Then, thinking better of it, he refrained. When they reached the shore, the tide was sufficiently far out to allow Cargill to show them the spot at which he had picked up the cartridge-case. Wendover still had a mental map in his head, and he recognised that the shot must have been fired by the man behind the groyne at the time when he was nearest to Neptune's Seat. If Stanley Fleetwood was even a moderate shot with an automatic, he could hardly have missed Staveley's figure at the distance. Sir Clinton seemed to become more keenly interested when they reached the shore. His detached manner thawed markedly, and he thanked Cargill again for having brought the evidence to light. “Oh, it was only an accident,” the Australian protested. “I wasn't looking for anything. It just chanced to catch my eye. Does it throw any light on things?” Sir Clinton obviously resented the question. “Everything helps,” he said sententiously. Cargill saw that he had been indiscreet. “Oh, I'm not trying to stick my oar in,” he hastened to assure the chief constable. “I just asked out of mere curiosity.” He seemed rather perturbed lest he should have appeared unduly inquisitive; and in a moment he changed the subject completely. “By the way, I heard someone mention in the hotel that a man called Derek Fordingbridge is staying somewhere hereabouts. Know anything about him? I came across somebody of that name in the war.” “He's staying at that cottage across the bay,” Wendover explained, pointing out Flatt's cottage as he spoke. “What sort of person was your friend?—in appearance, I mean.” “Oh, about my height and build, clean-shaved, hair darkish, if I remember right.” “This looks like your man, then,” Wendover assured him. “But you'll probably find him a bit altered. He's had some bad wounds.” “Has he? Pity, that. I say, I think I'll just go across the bay now and see if he's at home. I'm half-way there already.” Sir Clinton offered him a lift in the car; but on finding that it would be taking them out of their way, Cargill refused the invitation and set off alone across the sands. Before he started, Wendover gave him a warning about the quicksand near the wreck, lest he should stumble into it unawares. “That's an interesting find,” Wendover volunteered as they climbed the beach. “I didn't say anything in front of Cargill, but it occurred to me that his cartridge-case clears up one of the difficulties of the evidence.” “You mean that Billingford couldn't tell the inspector whether there was a single shot or a pair?” Sir Clinton inquired.