Mr. Lacey was the owner of a group of grocer’s shops scattered about West London. He had acquired the lease of Number 407, when the premises were given up by the late tenant, a clothier. He had never heard of Mr. Martin, and had certainly never written to him. He always signed himself John R. Lacey, and the signature on the letter found on Mr. Martin’s body bore no resemblance whatever to his handwriting. He had only once entered the cellars of Number 407, and had made no discoveries there of any kind. On Saturday he had left Liverpool Street at ten o’clock, to stay with his brother in Ipswich, and had not returned until the first train on Monday morning. He had sent no telephone message to Mr. Briggs, nor had he made any appointment with anybody to inspect the drains of Number 407. He had no key of the premises, having given the only two which so far as he knew existed to Houlder, the builder. He was utterly unable to throw any light whatever upon the incident, since more than a week had passed since he had visited Praed Street. Two other facts did Inspector Whyland discover. The first, which did not astonish him, was that the letter signed John Lacey had in all probability been typed upon the same machine as had been the envelope in which the numbered counter had been sent to Richard Pargent. The second, which was distinctly perplexing, was that the call to Mr. Briggs had been made from a call-box at Aldersgate station, apparently at the very time when Mr. Martin was known to have been there. Lastly, the automatic was identified as the property of Mr. Martin, and a fingermark on the counter corresponded to an imprint taken from the dead man’s hand. The significance of the curious butt found by the electrician in the lamp-holder was not so clear. It seemed reasonable to assume that nobody but the dead man had entered the premises after they had been locked by the foreman on Saturday morning. Whyland had examined all the doors and windows very carefully, and had satisfied himself that they bore no signs of violence. He could account for both keys, and although it was possible that a third key existed, it seemed unlikely that anyone had used it between 12.30 and two. Again, since the door had been found bolted on Monday morning, it was probable that the dead man had bolted it behind him, and that he was alone in the house when he died. The foreman had assured him that he had found the windows fastened inside, and that it was only by the use of a special tool that he had been enabled to open the one at the back. It looked very much as if Martin had himself fixed the butt in the lamp-holder. But why?