If, as seemed likely, the man who had made the fifth set of tracks on the river bank had really entered the house, his muddy boots must surely have left traces. Tanner therefore began with the floor, and crawling on his hands and knees backwards and forwards, scrutinised the cement-coloured surface. It was tiresome work, but at last he found what he thought looked like footprints. On the quay not far from the corner of the basin were a number of tiny mud-coloured spots. At first he could not connect these to make a complete whole, but by lying down on his face and using a lens he was able to find several other patches of coagulated sand, which he marked with a pencil; and when he had finished there showed out on the granolithic the nail patterns of two clearly marked heels with the corresponding middle portion of the soles in front. It was evident a man had stood with his back to the door, and facing the basin, and had remained there long enough to allow the moisture from the soles of his shoes to run down the nail heads, and settle on the floor. It was the work of a few seconds for Tanner to compare these marks with those of the fifth man on the river bank. They were identical. He resumed his search. There were no more footmarks, and he made but one other discovery. In the left-hand corner of the quay, at the very edge of the basin, and hidden behind the mooring rope of one of the boats, lay the stump of a cigarette. Clearly the intention had been to throw it into the basin, but it had just missed going down, and had fallen unnoticed. Tanner had a good working knowledge of cigarettes, but this one he could not place. The paper was yellow, and the tobacco very dark in colour. He thought it looked South American. But he was pleased with his find, for it seemed to have been but recently smoked, and as he put it away in his pocket, he thought he had perhaps gained a clue. An examination of the door handles and styles, winch handle, backs of chairs and similar objects with a powdering apparatus revealed several finger prints, but, alas! all too smudged and blurred to be of use. Nor could he find anything else of interest. He was disappointed that the boathouse had yielded so little. It was true that either the footprint or the cigarette end might prove valuable, but on the other hand neither were necessarily connected with the murder. Both might have got there in a perfectly ordinary and legitimate manner.