midnight
Ten minutes later Kerry was in bed , his short clay pipe between his teeth , and The Meditations of Marcus Aurelius in his hand . Such was his customary sleeping-draught , and it had never been known to fail . Half a pipe of Irish twist and three pages of the sad imperial author invariably plunged Chief Inspector Kerry into healthy slumber . It was close upon midnight when Detective-Sergeant Coombes appeared in a certain narrow West End thoroughfare , which was lined with taxicabs and private cars . He wore a dark overcoat and a tweed cap , and although his chin was buried in the genial folds of a woollen comforter , and his cap was pulled down over his eyes , his sly smile could easily be detected even in the dim light afforded by the car lamps . He seemed to have business of a mysterious nature among the cabmen ; for with each of them in turn he conducted a brief conversation , passing unobtrusively from cab to cab , and making certain entries in a notebook . Finally he disappeared .