"N or M?" is a gripping crime novel by Agatha Christie set during the turbulent times of World War II. The story follows the mismatched espionage duo Tommy and Tuppence Beresford, who are commissioned by the British Secret Service to search for enemy agents in a coastal hotel during the war. Amidst the oppressive atmosphere of war and the threat of spies hiding among civilians, they must use their skills and sharp wits to uncover the identity of the murderers. The plot unfolds in an exciting game of deception and intrigue as the protagonists attempt to reveal the truth behind the mysterious events. Christie's masterful storytelling and the complex characters make this work an essential part of crime literature.