“This one,” he went on, taking up the one the Canon had given him, “was carried by Templeton when he walked into Frattenbury yesterday afternoon. I’ve traced the marks of it along the field path. But he didn’t take it back with him—Canon Fittleworth lent him an umbrella. And this one,” he added, taking up the other, “I found under the stern seat of the dinghy. I’d almost made up my mind it had belonged to Templeton, but inquiry from the Canon seems to show it didn’t. After I’d found it I questioned Templeton’s man—Webb—though I took care not to let him see it.” “Why not?” asked the Chief Constable. “Because, sir, I never like to give anything away if I can possibly help it; and I thought, even then, that it might possibly have belonged to someone else. What I wanted to find out from Webb was whether there had been more than one walking-stick aboard the _Firefly_. And there hadn’t. So now we know that this stick must have been left by someone else who went out to the yacht.” “Exactly,” said the superintendent. “And somebody else knows it, too.” “Who?” asked Major Renshaw. The superintendent and Colson exchanged meaning glances, and answered simultaneously: “The man who left it there.” And Colson added: “He made a bad mistake. And it’s mistakes that are the best clues. That’s my experience.” The Chief Constable and the superintendent examined the stick carefully. It was a very ordinary plain ash walking-stick, with a crook handle. The only noticeable thing about it was that a small piece had been chipped off the handle. Otherwise there was nothing remarkable about it. Colson sat lost in thought. Presently his face cleared a little. “I’ve got an idea,” he said; “it’s only a sort of forlorn hope. But I may as well try it. By the way, I promised Gadsden he should be relieved, sir,” he added to the superintendent. “He’s been at Marsh Quay since early morning.” The superintendent touched a bell, and a constable entered. “Is Peters in?” “Yes, sir.” “Tell him to report for duty.” “Very good, sir.” Peters came in, and the superintendent gave him some brief instructions. Then Colson spoke. “I want you to do exactly what I say, Peters,” he said. “When you get to Marsh Quay it will still be daylight. Ride your bicycle there and leave it close to the shore. Then take one of the little canoes and paddle out to the yacht—the _Firefly_. Don’t in any way touch the dinghy that’s moored to her. Get on the yacht’s deck and stay there. Do you understand?” “Yes, sergeant.”