N or M

It is World War II, and while the RAF struggles to keep the Luftwaffe at
bay, Britain faces an even more sinister threat from ‘the enemy within’
– Nazis posing as ordinary citizens. With pressure mounting, the
Intelligence service appoints two unlikely spies, Tommy and Tuppence
Beresford. Their mission: to seek out a man and a woman from among the
colourful guests at Sans Souci, a seaside hotel. But this assignment is
no stroll along the promenade. After all, N and M have just murdered
Britain’s finest agent.