Rumpled London policeman Runcorn is sent to a lonely Welsh island for Christmas, where he gets pulled into the case of the murder of Olivia Costain, the town vicar's lively single sister. Runcorn employs his bare-knuckle investigative skills in interviewing Olivia's family and her various suitors, to the chagrin of the local constable, Sir Alan Faraday, whose pursuit Olivia rejected. Runcorn's modest, unflashy ways carry this moody, understated mystery.