Irene (Greer Garson) is the wife of Victorian "man of property" Soames Forsyte (Errol Flynn), having married without love but after many proposals. Rebelling against her husband's preoccupation with material possessions, a list in which she is included, Irene falls in love with unconventional architect Philip Bosinney (Robert Young (actor)), who is engaged to Soames' niece June (Janet Leigh), one of Irene's closest friends. Soames learns of Irene's affair with Bosinney, and rather than allowing Irene to leave him, he reasserts his physical rights. When Soames and Bosinney discover that Irene has run away, Bosinney rushes out in the foggy London streets after her, only to be run over in an accident. After Irene learns of Bosinney's death she takes refuge with Soames' cousin Young Jolyon (Walter Pidgeon), who is June's estranged father but has sympathy for Irene's plight. Irene and Young Jolyon eventually marry, after Irene spurns Soames's attempts at reconciliation.