Plot
Polish Viktoria Kowalska lost her home and her husband in the German occupation of Poland and is imprisoned in the Bergen-Belsen concentration camp. She befriends another prisoner, Karin Dernakova, who dreams of reuniting with her young son, Christopher, sent to live in San Francisco with a wealthy aunt.
Karin dies shortly before the camp is liberated; seeking a better life, Viktoria uses Karin's papers to assume her identity, destroying her own papers. When the camp is liberated by the Allies, Viktoria is interviewed by Major Marc Bennett, who secures a place for her in a camp for displaced people. Viktoria writes to Karin's aunt Sophia in San Francisco but receives a cable from lawyers that Sophia has died.
Four years later, Viktoria, using Karin's name, travels to New York City, where she meets Chris's guardian, Alan Spender, Sophia's distant relative. Viktoria intends to gain custody of Karin's son, but Sophia has left her fortune to Chris when he comes of age. Realizing Alan is attracted to her and that it will be easier to stay in the country with an American husband, she allows Alan to romance her, and they soon marry. Alan takes "Karin" to San Francisco, where she settles into Sophia's Italianate mansion on Telegraph Hill, where Chris lives with Alan and his governess Margaret. Tensions mount between Karin and Margaret, who has raised Chris, loves Alan, and resents Karin.
Karin is alarmed at a burned, dangerously damaged playhouse overlooking the hill that Chris claims to have damaged with an explosion from his toy chemistry set. He and Margaret beg her not to tell Alan; Karin is perplexed when Alan revels he already knows about it. As Karin investigates the playhouse, she is startled by Alan, nearly falling to her death through a hole in the floor. Alan rescues her but is alarmed by her startled behavior.
At a party, Karin is pleased to meet Marc Bennett again, who clearly remembers her; he was Alan's schoolmate and is a partner at the law firm handling Sophia's affairs. They are attracted to each other, but she keeps a respectful distance.
The brakes on Karin's car fail on a day when Chris was supposed to be with her. She escapes unharmed but contacts Marc, telling him that she believes Alan is behind the accident. If Chris were to die, Alan would inherit Sophia's money.
Intending to ask for help, Karin goes to Marc’s office, but Alan encounters her in the lobby and grows suspicious when she pretends to have mistaken her dentist's address. Marc calls to check up on her, inviting Karin and Alan to dinner that night; Alan privately expresses concern to Marc about Karin's paranoid behavior, and Marc privately reports to Karin that the mechanic's report on the car accident was inconclusive. She reveals her true identity to Marc, who does not blame a concentration camp survivor for wanting a better life. He tells Karin that he is in love with her.
Karin discovers Sophia's obituary confirming that the cable to her was sent three days before Sophia's death—proof that Alan sent the cable before killing Sophia. Her attempt to phone Marc is thwarted when Alan does not leave her alone for the entire evening. When Alan brings her orange juice, she is sure her glass has been poisoned. When he briefly leaves the room, she attempts to call the police, but Alan left the phone off the hook in another room. Returning, he coerces her into drinking the orange juice before drinking his own. He confesses that he murdered Sophia and that he has mixed an overdose of sedatives into her orange juice. Karin tells him that she switched the glasses and he has poisoned himself. She tries to telephone a doctor, but the phone is still off the hook. Margaret is awakened by the commotion and Alan begs her to phone a doctor. Realizing that he does not love her and he will never stop trying to kill Chris, Margaret watches as Alan dies.
Margaret is arrested for refusing to aid Alan, and Karin leaves the house with Marc and Chris to begin a new life.
