Adapted from Josephine Tey's novel, a man accused of murder escapes and tries to prove his innocence with the help of the constable's daughter.
An angry man calls his wife Christine a liar, and she slaps him. Robert Tisdall (Derrick De Marney) finds Christine unconscious on the beach and runs off. Two women find her and see him running. Police say she was strangled with a belt recently. Robert is questioned and says his coat was stolen. When he is told she left him 1200 pounds, he faints. Erica Burgoyne (Nova Pilbeam) cares for Robert, who uses his lawyer's glasses to escape from the courthouse. Erica finds Robert in her car and says she is the constable's daughter. Robert buys petrol, but Erica tells him to get out. As he hides in an abandoned house, she leaves but does not tell police.
At dinner Erica's family discusses Robert's lack of money and food. Erica takes food and money to him. Police see a paper Robert threw out and search. Robert and Erica run and drive off. At an inn Erica asks about the raincoat, and answers cause a fight. Robert comes in and bruises his head. Erica helps Robert look for the tramp Old Will. Erica stops to see her Aunt Margaret (Mary Clare), and her uncle (Basil Radford) invites Robert in to the birthday party. They leave, and Margaret calls Erica's father, Col. Burgoyne (Percy Marmont), who calls police to stop Erica and tell her to call him. When police stop them, Robert causes Erica to drive off.
At night they hide by a railroad. At a lodging house Robert asks for Will and sleeps. In the morning he finds Will (Edward Rigby) and takes him to Erica's car, and they flee. Will gives Robert his coat but with no belt; he says the man has an eye twitch. They drive into an old mine that collapses under the car, and Robert barely saves Erica. After being questioned, Erica tells her father that Robert is not a murderer. He shows her his letter of resignation and sends her to her room, where she cries. Robert comes in her window to say good-bye before giving himself up. They find matches from the Grand Hotel. Erica goes there with Will in fine clothes. The drummer wearing black face in the band sees Will, and his eyes twitch. Will dances with Erica while Robert is arrested. The drummer is nervous, takes a pill, plays poorly, and collapses. Erica goes to help him and calls Will, who identifies him. He confesses he used the belt to strangle her. In the final scene Erica has her father invite Robert to dinner.
Director Alfred Hitchcock presented his favorite theme of an innocent man accused of crime trying to prove his innocence with the help of a woman while on the run, enabling the audience to root for them to survive suspenseful situations and achieve resolution in the end.