“Stop, stop. Now remember, Bob, that’s an old theory. Everything we discuss to-night must be a new idea. That theory presupposes that the murderer was on the yacht first. Put it away. Tell me what other alternatives were there? I’m out of my depth here.” He thought carefully for a few minutes and replied: “Only three, as far as I can see. First, some boat from outside came in. Not likely, because one of the canoes was found unfastened in the morning. Mrs. Yates told me this. Secondly, that the murderer went out to the yacht in the canoe after Templeton had returned. Also unlikely, because he would scarcely have transferred his stick to the dinghy. Thirdly, that hardly seems probable.” “Then it’s worth consideration, Bob. You’ve gone, too much, on probabilities. Let’s have this ‘thirdly,’ please.” She had never heard of the theologian’s famous dictum, “_Credo, quia incredibile est_,” but it was the same line of reasoning. “It’s this, then. Templeton himself rowed the murderer out in the dinghy, the latter sitting in the stern and laying his stick down as he sat. They both went on board and the murder was committed. Now comes the improbable part. The murderer rowed back to shore in the dinghy, ran the canoe down to the water, paddled back towing the dinghy, made the latter fast again to the yacht, and finally returned in the canoe, dragging her up again, but forgetting to fasten her painter to the post as before.” For some minutes Mrs. Colson gazed steadily into the fire in silence. Colson refilled and lighted his pipe, and waited. Then she said: “I see. But he might have had a very artful object in doing this. If he went on board with Templeton, and he didn’t live at Marsh Quay, he must have met him somewhere else first—and gone with him. Well, if he’d only landed in the dinghy and left it on the shore, it would have been a clear proof that Templeton had taken him on board—and if, by any chance, they had happened to be seen by anybody _first_—he would naturally have been suspected. His very best plan would be to leave the dinghy fast to the yacht, and he could only have done so in the way you say.” Colson smoked for a moment or two. “It was taking a big risk—risking time for getting clear away.” “It was worth it, Bob. Would it make much noise—getting the canoe down to the water?” “Oh, no; it was lying on a patch of grass—the grass grows right down to the water’s edge, you know—and if the tide wasn’t quite up—and it wasn’t—there would be soft, sandy mud just there between the green and the water’s edge. The stony part of the beach is nearer the quay. And the canoe is almost light enough for a strong man to carry. No, there needn’t have been any noise.” She looked at him and smiled. “We’re getting on, then.” “There’s another point in favour—ah, you’ve scored again, dear—I was just going to say that it would make things look so improbable.” They both laughed heartily. Suddenly a little shadow came over her face.