“About five minutes past nine,” replied Ponting. “The church bell had struck nine when the row began.” “Hm!” grunted Miller, glancing at Thorndyke. “Well, that is all we wanted to know, so we need not keep you from your work any longer.” He rose, and being let out with great alacrity, stumped down the stairs, followed by Thorndyke and me. As we came out into the street, he turned to us with a deeply disappointed expression. “Well,” he exclaimed, “this is a suck in. I was in hopes that we had pounced on our quarry before he had got time to clear away the traces. And now we’ve got it all to do. You can’t get round an alibi of that sort.” I glanced at Thorndyke to see how he was taking this unexpected check. He was evidently puzzled, and I could see by the expression of concentration in his face that he was trying over the facts and inferences in new combinations to meet this new position. Probably he had noticed, as I had, that Ponting was wearing a tweed suit, and that therefore the shreds of clothing from the fence could not be his unless he had changed. But the alibi put him definitely out of the picture, and, as Miller had said, we now had nothing to give us a lead. Suddenly Thorndyke came out of his reverie and addressed the superintendent. “We had better put this alibi on the basis of ascertained fact. It ought to be verified at once. At present we have only Ponting’s unsupported statement.” “It isn’t likely that he would risk telling a lie,” Miller replied gloomily. “A man who is under suspicion of murder will risk a good deal,” Thorndyke retorted, “especially if he is guilty. I think we ought to see Mrs. Barnett before there is any opportunity of collusion.” “There has been time for collusion already,” said Miller. “Still, you are quite right, and I see there is a light in their sitting-room, if that is it, next to Ponting’s. Let us go up and settle the matter now. I shall leave you to examine the witness and say what you think it best to say.” We entered the building and ascended the stairs to the Barnetts’ flat, where Miller rang the bell and executed a double knock. After a short interval the door was opened and a woman looked out at us inquisitively. “Are you Mrs. Frederick Barnett?” Thorndyke inquired. The woman admitted her identity in a tone of some surprise, and Thorndyke explained: “We have called to make a few inquiries concerning your neighbour, Mr. Ponting, and also about certain matters relating to your family. I am afraid it is a rather unseasonable hour for a visit, but as the affair is of some importance and time is an object, I hope you will overlook that.” Mrs. Barnett listened to this explanation with a puzzled and rather suspicious air. After a few moments’ hesitation, she said: