The House in the Square

Peter Standish (Tyrone Power) is an American atomic scientist who is working in a nuclear laboratory in London. He is brought back to 1784, where he is thought to be the American cousin of the Petigrews who, according to history, will soon romance and marry Kate. Peter falls for Kate, but he is more interested in her sister Helen (Ann Blyth), of whom he has never found any records. They fall in love, despite Peter's awareness that he has to marry Kate in order to not change history.