N or M?

Tommy and Tuppence Beresford, middle-aged and sidelined by the war effort, are handed a counter-espionage assignment at a quiet seaside guesthouse. N or M? places Agatha Christie's married detectives in wartime Britain, where two enemy agents are known to be hiding among a small group of guests. The puzzle is one of identity rather than murder, and Christie works it out through conversation, observation and the social manners of a boarding house. The wartime setting gives the book an unusual immediacy among her novels, and the partnership between the Beresfords supplies its humour. Things worth knowing: • A Tommy and Tuppence mystery rather than a Poirot or Marple case • Wartime espionage plot resolved through deduction, not violence • A closed circle of suspects inside a single guesthouse setting • Reads independently of the other Beresford novels Suited to classic crime readers and collectors completing a Christie set. This HarperCollins edition is available through Boipoka.