After a rapid engagement, Ann Hamilton (Katharine Hepburn), the dowdy daughter of a chemist, weds handsome industrialist Alan Garroway (Robert Taylor), knowing little of his family or past. Alan transforms Ann into an elegant society wife, but becomes enraged whenever she asks about Michael (Robert Mitchum), his mysterious long-lost brother. Ann begins to suspect her new husband of the worst when she digs into the Garroway history and learns that Michael is believed to have been murdered.