Dial M for Murder (1954)

Tony Wendice, a cold and calculating retired tennis player, plans the perfect crime against his wife Margot, whom he suspects of infidelity, but mostly because he wants her fortune. To carry it out, he blackmails an old college classmate and convinces him to commit the crime in his absence. This is certainly an important film in Alfred Hitchcock's filmography, packed with tension and an intriguing development that takes place in a single scenario and with few characters, played by a magnificent cast.