Dial M for Murder

How this film uses it

Almost everything happens in the Wendices' London flat, like a stage play. You get to know the door, the stairs and the desk so well that small changes stand out.

Where to see it

The planning scene. Tony invites Swann to the flat and lays out the murder plot in the same rooms where it will play out.

How this film uses it

Tony lays out the entire plan to Swann before it happens, and you hear every step. The film stops being a whodunit and turns into a question of how the plan will fall apart. You watch the police stumble toward what you already know.

Where to see it

Tony's pitch to Swann. He tricks Swann into leaving fingerprints on a letter, then threatens to expose him unless he kills Margot.

How this film uses it

The latchkey hidden under the stair carpet moves the whole plot. Tony hides it, Swann uses it and the police later use it to catch Tony. By the end, 1 small key stands for how carefully Tony planned and how carelessly he assumed.

Where to see it

The key trap. Hubbard brings Margot to the flat, and she cannot open the door with the key from her handbag. When Tony finds his own key missing, he retrieves the hidden one from under the stair carpet, and that proves his guilt.

How this film uses it

The murder plot depends on a phone call. Swann waits in the flat for it to ring, and Tony hears the struggle through the receiver when it happens. You get the horror from the sound alone.

Where to see it

The phone call. Tony rings from the party and Margot answers, then Swann attacks her. Tony listens to her pleading for help.

How this film uses it

Inspector Hubbard works out the truth from objects. Margot's handbag holds Swann's own latchkey, which tells him Swann put the Wendices' key back right after opening the door. You follow his reasoning and not a confession.

Where to see it

Hubbard's visit. He tricks Tony into revealing that his latchkey is in his raincoat, then swaps coats with him and sets a trap.