Ember gave just a little nod, opened a safe that stood in the corner, pushed the papers into it, and pocketed the key. It was a little later that he found the first spot of candle grease. It was half-way up one of the side passages, on the spot where Jane had been standing when he and Molloy entered the laboratory the evening before. He looked at it for a long time very thoughtfully before he took his torch and proceeded to a systematic search of the passages. He found no living person, but came upon dropped wax in three more places, at the edge of the well, by the headland exit, and half-way down the steps to the beach. He came slowly back along the main passage, and stood for some time with his light focused on the sand which he had spread at the foot of the stair. There was no footmark upon it, but he was prepared to swear that it was not as he had left it. He had scattered the sand loosely, and it was pressed down and too smooth. He thought that it had been smoothed by a hand passing over it. He mounted the first two steps. The thread of cotton which he had fastened across the stairway was still there. He bent beneath it, came to the top, and threw his light full upon the back of the panelled door. The second piece of cotton was gone. He flashed the ray upon the floor once—twice. The third time he found what he was looking for, a fine black thread lying across the threshold. It ran out of sight under the door. Some one had gone out that way since Mr. Ember had come in. Who? Not Molloy—impossible that it could have been Molloy. Ember passed through the panel, closed it behind him, and walked slowly and meditatively along the corridor to the library, still pursuing his train of thought. Molloy would have blundered through that first piece of cotton without ever feeling it at all, just as Molloy’s foot in its heavy boot would have been unaware of the sand. If it was a woman who had passed—now who would have used a candle in the passages? Not Raymond. She had more than one electric torch which she used constantly for night work. But Renata, the little soft-spoken stupid mouse of a thing, if she had a fancy to go spying, she’d take a candle; yes, and let it gutter too. Mr. Ember’s instinct for danger had always reacted to this question of Renata Molloy. Over and over again there had been the tremor, the response, the warning prick. An extreme regret that he had not arranged for a convenient accident to overtake Renata possessed Jeffrey Ember. The omission, he decided, should be rectified with as little delay as possible. He locked the library door and went to the telephone.