Karen Stone (Vivien Leigh), an acclaimed American stage actress, and her businessman husband are off on holiday to Rome. On the plane, her husband suffers a fatal heart attack. Karen decides to stay in Italy and rent a luxury apartment in Rome. The Contessa Magda Terribili-Gonzales (Lotte Lenya) soon introduces her to a young Italian man, Paolo (Warren Beatty), who is actually a highly paid professional gigolo. Karen and Paolo begin an affair, but it soon becomes obvious that Paolo is in it only for personal gain. He is soon bored by Mrs. Stone and leaves her to pursue a young American film actress (Jill St. John). Ridiculed by the Contessa, chastised by her friend Meg (Coral Browne) and abandoned by Paolo, Mrs. Stone is soon utterly debased enough to surrender herself to a ragged, mysterious young man who has been following her obsessively. In the end, it seems as if Mrs. Stone has literally given up her life.