Daphne du Maurier - The Alibi

Charles Fenton is bored: bored by his job, by his wife and by his routine. In the middle of a Sunday afternoon walk by the Thames with his wife, Edna, he decides to kill somebody. Sending Edna home, he decides that he will walk down three streets and then stop at No. 16 – the same number as the day's date – and kill whoever answers the door.