Chicago subway worker Lucy (Sandra Bullock) is infatuated by businessman Peter (Peterg Gallagher), a commuter who regularly uses her station and who she only ever sees from a distance. One day, Peter is almost hit by a train, but Lucy manages to save him at the last moment; then, as she sits by his side while he lies unconscious in a hospital bed, his family arrive and mistake her for his new girlfriend.

 Happy to be welcomed into the home of her dream partner, Lucy tries to gather the strength to set the record straight, but the situation only becomes more complicated when she starts falling in love with Peter's brother Jack (Bill Pullman).