After Connie Doyle (played by Ricki Lake) gets kicked out by her abusive boyfriend, she wanders onto a train and ends up sharing a compartment with a wealthy couple, Hugh (played by Brendan Fraser) and Patricia Winterbourne (played by Susan Haskell), who are also expecting a baby. During the train journey, there is a terrible accident, and Connie wakes up in the hospital to learn that Patricia has died, while she and Hugh have survived. Due to the confusion created by the accident, hospital staff and the Winterbourne family assume that Connie is Patricia, and she goes along with it because she has no other family or support.
Hugh's mother, Grace (played by Shirley MacLaine), takes Connie in, and she tries to make the best of her new life, which includes getting accustomed to the trappings of wealth and being treated as part of the Winterbourne family. Along the way, she falls in love with Hugh's estranged brother, Bill (played by Loren Dean), who initially sees her as an impostor but eventually warms up to her. Connie and Bill become closer after a trip to Mexico, where she reveals her true identity to him. But their happiness is short-lived when Connie's ex-boyfriend, Steve (played by Kieran Mulroney), shows up and threatens to reveal who she really is.
Connie struggles to keep her secret and protect the life she has come to love, but Steve is determined to ruin everything. Affected by Connie's plight, Bill tries to help her by confronting Steve, but things turn violent. In the end, the truth is exposed, but the Winterbourne family forgives Connie and welcomes her back into their circle. Connie and Bill also reconcile, and Hugh, who has meanwhile fallen in love with Connie, supports their relationship. In the epilogue, Connie has given birth to a baby girl, and the Winterbournes are a happy, extended family.
