"I quite agree with the doctor's evidence," said Quarles, "but he is not a detective. Let me reconstruct what happened. Dr. Smith came to the cove either with a companion or to meet someone. Possibly the doctor had a drink, let us say from a bottle in the boat's locker. I do not press this point, but it would make the work easier. The companion pushed the doctor into the water, and with a boathook--there was one lying on the rocky ledge--he held him under until he drowned. Once the hook was fixed into the collar of the coat it would be comparatively easy. Afterward a piece of rock tied to the body would keep it under water. I suggest this could be done with least danger in the cove next to the one where the boat was kept. It is deeper, darker, and would not be likely to receive so much attention when it became known that the doctor was missing. So the body would be securely hidden. "Then the boat, as soon as it was dark enough, was towed out to the end of the spur and scuttled. The water is shallow there, and as soon as the wind got up it was battered to pieces and presently the wreckage came ashore. Why shouldn't the body have been left to come ashore too? you may ask. Old Clay is learned in the currents of this part of the coast, and he will tell you there is no certainty what will happen to wreckage. During a southwesterly gale it may be thrown up on the shingle; at any other time it may be carried out to sea. "At the time of the murder it was quite calm, and it was necessary that the body should be found. The murderer was in no hurry, and at first too many people went round to look at the coves for it to be safe for him to take any steps. But he got his opportunity probably on the night you spent in London when you first mentioned the case to me, you remember. He got up the body from its hiding-place, and with the boathook pulled it partly through the water and partly over the rocks, and fixed it in the place where it was found, the one place where Clay is certain wreckage never comes ashore." "I think the theory is fanciful, professor." "I grant that only the brain of a master criminal could conceive such a crime. There was my difficulty. Where was this master criminal to be found?" "And what was his motive?" I said. "There is the insurance money, but that comes to the wife. She could not have carried out such a fantastic crime, nor do I believe for a moment that she instigated it." "On both points I am with you," said Quarles. "Now let us consider another question--the identity of the dead man." "Surely there is no question about that? The official from the insurance office----"