Adam Verver, a US billionaire in London, dotes on daughter Maggie. An impecunious Italian, Prince Amerigo, marries her even though her best friend, Charlotte Stant, is his lover. She and Amerigo keep this secret from Maggie, so Maggie interests her widowed father in Charlotte, who is happy with the match because she wants to be close to Amerigo. Charlotte desires him, the lovers risk discovery, Amerigo longs for Italy, Maggie wants to spare her father's pain, and Adam wants to return to America to build a museum. Amidst lies and artifice, what fate awaits adulterers?

A saga of class relations and changing times in an Edwardian England on the brink of modernity, the film centers on liberal Margaret Schlegel, who, along with her sister Helen, becomes involved with two couples: wealthy, conservative industrialist Henry Wilcox and his wife Ruth, and the downwardly mobile working-class Leonard Bast and his mistress Jackie.