Twelve o'clock
He let himself in with his latch-key , went into his dining-room , and sat down dressed as he was to wait . He listened through minute after minute for the expected step . The window was open -LRB- for the midsummer night was warm -RRB- , and all the sounds of belated and revelling London floated vaguely in the air . Twelve o'clock boomed softly from Westminster , and made the heavy atmosphere drowsily vibrate with the volume of the strokes . The reverberation of the last had scarcely died away when a light , measured footfall made him sit up . It came nearer and nearer , and then , after a moment 's hesitation , sounded on his own doorstep . With that there came the tap of a cane on the window .