Helen Ferguson (Stanwyck) is pregnant and alone: her boyfriend wants nothing with her, so he sends her on a train ride where she meets a friendly couple, Patricia and Hugh Harkness. Unfortunately, the train derails, and her identity is confused with the now-deceased Patricia (Hugh also died in the crash). With no money and zero connections, Helen decides to don the identity.
She finds out the Harkness family is loving and caring, especially Bill Harkness (Lund), and she lives a rather happy life until her ex-boyfriend, Stephen (Lyle Bettger) starts blackmailing her.
This film shows the following tropes:
- Adaptational Alternate Ending: The original novel ends with Stephens murder unsolved. Helen and Bill wait for the police in defeat while suspecting each other of the crime. The film ends on a much happier note; once the police arrives they notify the couple they have found Stephens killer and the two are absolved.
- And Now You Must Marry Me: Stephen forces Helen to marry him so that he can inherit the Harknesses fortune and make Helens life miserable.
- Blackmail: Either Helen gives Stephen $500 or hell spill the beans about her identity. Of course, this is just a way to trick her into meeting up with him and then being forced to marry him.
- Blackmail Backfire: Not only was Helen ready to kill Stephen, so was Bill.
- Convenient Miscarriage: Averted: Helen and the baby survive the train derailment.
- Cover Identity Anomaly: Helen tries to convince her doctors that she isnt Patricia Harkness, but they think she's just confused because of the train crash she survived. The Harkness family then takes her in (never knowing what Patricia looked like). She decides to go along with it because shes penniless and has a newborn baby in tow, but she makes a lot of simple mistakes about Hugh.
- False Confession: Bills mother finds out that theres something odd happening with Helen, and she connects the dots about Stephen Morley, so she creates a false confession to the murder of Stephen, hoping that it will help Helen from going to jail.
- Femme Fatale: Stephens current girlfriend that we meet in the beginning of the film. It turns out that she was the one who killed him, not Bill.
- How We Got Here: The film begins with Helens narration when the police are coming to the Harkness household, and she knows that shell probably go to jail.
- Mistaken Identity: Helen and the real Patricia Harkness were both in the bathroom (and both pregnant) when the train derailed, and conveniently, Helen put on Patricias wedding ring to make sure that she wouldnt lose it. The authorities then thought that Helen was Patricia.
- Out-of-Character Alert: This happens constantly to Helen as she tries to pretend to be Patricia: she doesnt know Hughs favourite song, didnt know that Hugh had a brother, signs her real name when trying out a pen (Bill is the only one to witness this), etc. The family think this is just a result of the train accident, but Bill is the only one that figures out that Patricia isnt really Patricia. But he doesnt care.
- Romancing the Widow: Bill falls for Helen and tries to romance her, but she rejects him because of her false identity.
- Tempting Fate: Helen mentioning that wearing someone else's wedding ring is bad luck. Cue to the train derailing.
- Vehicle-Roof Body Disposal: Bill gets rid of Stephens body by throwing it on a train going out of town.