N or M?
This atmospheric story, set during World War Two, finds Tommy and Tuppence doing what they do best – having an adventure. These unlikely Intelligence Service spies decide to help Queen and country by tracking down two ruthless traitors. The only clue to the traitors’ identities is a government agent's dying words that lead them to the Sans Souci boarding house, where it’ll take some extremely subtle detection work to establish which of the guests are the treacherous N and M.