N or M?: A Tommy and Tuppence Mystery (Tommy and Tuppence Mysteries Book 3)

Set during World War II, Agatha Christie’s riveting novel in her Tommy and Tuppence series follows the unlikely espionage agents as they pursue a pair of Nazi spies who have murdered Britain’s top agent—now a movie on both Acorn TV and PBS.

World War II is raging, and while the RAF struggles to keep the Luftwaffe at bay, Britain faces a sinister threat from "the enemy within"—Nazis posing as ordinary citizens.

With pressure mounting, the intelligence service appoints two improbable spies, Tommy and Tuppence Beresford. Their mission: to seek out a man and a woman from among the colorful guests at Sans Souci, a seaside hotel. But this assignment is far from an easy stroll along the promenade—N and M have just murdered Britain's finest agent and no one can be trusted.