John Denby, the owner of the Great Eastern Railroad, and his wife have mourned for fourteen years the loss of their little daughter Mary, who was kidnapped at the age of three. On the day that engineer John Graham is unfairly sentenced to life imprisonment for wrecking a train, a stranger who claims to be Mary's kidnapper takes the adolescent Mary to the Denby house, saying that he took her as compensation for the loss of his own child. Several years pass, during which the Denbys, particularly young Jack, become greatly attached to their long-lost Mary. Believing that Graham is innocent, Jack finally secures his freedom, whereupon Graham claims Mary as his own daughter, revealing that he had tricked Denby into caring for the girl during his confinement in prison. Mary's affections are divided between her real father and her foster family, and she is at a loss for what to do until Jack resolves the problem by proposing to her.