The setting is a great house in Cornwall, which has been inherited by young Philip Ashley on the death of his uncle and surrogate "father." Although deeply attached to his ancestral home, the uncle had gone to Rome, married a young Italian widow of short acquaintance, and then died under what his friends and family consider mysterious circumstances. When the widow, "cousin" Rachel, comes to visit Philip, she is received coolly at first, but her charm and grace, and the fact that she too comes from Cornish lineage, soon wins her friends—and the ardent devotion of Philip himself. This does not sit well with Louisa Kendall, a lifelong friend and neighbor who is in love with Philip, or with her father, Nicholas, who has acted as trustee for Philip's inheritance. As his attraction for the alluring Rachel increases, Philip's health declines, and he is soon the victim of "Roman fever" himself, confirming, to Kendall and Louisa, the fear that Rachel, who is treating Philip with a specially prepared herb tea, is actually poisoning him. The arrival of a faintly sinister friend of Rachel's from Rome; Philip's decision to sign over his estate to her; and Rachel's cold refusal of Philip's offer of marriage, even after they have become lovers—all add to the mounting tension, and lead to the breath-stopping final scene, the famous "twist" ending which leaves nagging doubts as to where guilt, and evil, should fairly be assigned.
Famous as a bestselling novel, and then a motion picture classic, this haunting, suspense-filled study of intrigue and suspicion is offered here in a compelling, deftly-written stage adaptation, which has become an established favorite in the British theatre.