In a mansion in Caulfield, Illinois, Patrice Harkness and Bill Harkness are waiting for the police. Meanwhile, she recalls her life in San Francisco. The eight-month pregnant Helen Ferguson is dumped by her boyfriend, the crook Stephen 'Steve' Morley, who gives a train ticket to her to New York to stay with his new girlfriend. In the train, Helen befriends the also pregnant Patrice Harkness and her husband Hugh Harkness that are returning from Europe. When they go to the toilet, Patrice asks Helen to hold her wedding ring to avoid losing it, but there is an accident and only Helen survives. She is mistaken by the Hatkness family as being Patrice and welcomed by Mrs. Harkness, Mr. Harkness and Bill at home. Helen decides to pose of Patrice thinking in the future of her baby Hugh and the family treats her like a daughter. Out of the blue, Steve meets Helen in a club and blackmails her, promising to destroy the lives to Mr. and Mrs. Harkness. Now Helen realizes that she must kill Steve to protect her son and the old couple. What will she do?