It was close upon nine when he set out. I had no idea how long he might be, but I sat stolidly puffing at my pipe and skipping over the pages of Henri Murger’s “Vie de Bohème.” Ten o’clock passed, and I heard the footsteps of the maid as they pattered off to bed. Eleven, and the more stately tread of the landlady passed my door, bound for the same destination. It was close upon twelve before I heard the sharp sound of his latch-key. The instant he entered I saw by his face that he had not been successful. Amusement and chagrin seemed to be struggling for the mastery, until the former suddenly carried the day, and he burst into a hearty laugh.

“I wouldn’t have the Scotland Yarders know it for the world,” he cried, dropping into his chair; “I have chaffed them so much that they would never have let me hear the end of it. I can afford to laugh, because I know that I will be even with them in the long run.”

“What is it then?” I asked.

“Oh, I don’t mind telling a story against myself. That creature had gone a little way when she began to limp and show every sign of being foot-sore. Presently she came to a halt, and hailed a four-wheeler which was passing. I managed to be close to her so as to hear the address, but I need not have been so anxious, for she sang it out loud enough to be heard at the other side of the street, ‘Drive to 13, Duncan Street, Houndsditch,’ she cried. This begins to look genuine, I thought, and having seen her safely inside, I perched myself behind. That’s an art which every detective should be an expert at. Well, away we rattled, and never drew rein until we reached the street in question. I hopped off before we came to the door, and strolled down the street in an easy, lounging way. I saw the cab pull up. The driver jumped down, and I saw him open the door and stand expectantly. Nothing came out though. When I reached him he was groping about frantically in the empty cab, and giving vent to the finest assorted collection of oaths that ever I listened to. There was no sign or trace of his passenger, and I fear it will be some time before he gets his fare. On inquiring at Number 13 we found that the house belonged to a respectable paperhanger, named Keswick, and that no one of the name either of Sawyer or Dennis had ever been heard of there.”

“You don’t mean to say,” I cried, in amazement, “that that tottering, feeble old woman was able to get out of the cab while it was in motion, without either you or the driver seeing her?”