the hour of one
`` Good night , Mr. Forsyth , '' I replied ; and , having conducted my late visitor to the door , I closed and bolted it , switched off the light and went upstairs . My patient was chief officer of one of the P. and O. boats . He had cut his hand rather badly on the homeward run , and signs of poisoning having developed , had called to have the wound treated , apologizing for troubling me at so late an hour , but explaining that he had only just come from the docks . The hall clock announced the hour of one as I ascended the stairs . I found myself wondering what there was in Mr. Forsyth 's appearance which excited some vague and elusive memory . Coming to the top floor , I opened the door of a front bedroom and was surprised to find the interior in darkness . `` Smith ! ''