Dial M For Murder (1954)

In Alfred Hitchcock's classic thriller, remade as A Perfect Murder (1998):

• the story: charming and sophisticated husband and ex-tennis champion Tony Wendice (Ray Milland) blackmailed or "influenced" petty criminal Captain Lesgate/Swann (Anthony Dawson), a former classmate, to commit the "perfect murder" for £1,000 pounds cash - the killing of his wealthy wife Margot Wendice (Grace Kelly) in order to inherit her fortune; she was engaged in an affair with TV mystery writer Mark Halliday (Robert Cummings)
• director Hitchcock's cameo: in a class reunion photograph at Cambridge Univ, including both cigar-smoking Capt. Lesgate and Tony seated across the table from him
• the scene of Tony on the phone and dialing M to reach his wife (although tension was intensified and the plan was botched when his watch stopped and his call at 11:00 pm - by dialing M - was later than expected by about 8 minutes)
• the murder set-up - and the 3-D effect of Margot while being strangled reaching back - into the audience from the screen - searching for a weapon (a pair of scissors) to defend herself and kill hired assassin Swann by stabbing him in the back; when he theatrically fell to the floor onto his back, the blades of the scissors were pushed more deeply into his body

• the concluding scene in which the guilty Tony opened the door with the crucial duplicate key (Margot's front-door key stolen from her handbag by Tony, and planted for Swann's use) that he had retrieved from under the rug on the stairs outside the apartment; earlier, no key had been found on the dead assassin Swann (and there was no forced entry either, because he didn't have mud on his shoes) - Swann had entered using the planted key and immediately replaced it under the stairs' rug; when Tony entered (after using the planted key) and turned, he realized he had been found out: (Inspector Hubbard (John Williams): "Once he opens that door, we shall know everything")