Walking through London's West End after a night at the theater, Amory Ames and her husband Milo run into some old friends: wealthy investor and former actor Gerard Holloway and his wife, Georgina. When Holloway invites them to the dress rehearsal of the new play he's directing, Amory readily accepts. However, Amory is shocked to learn that Holloway has cast his mistress, Flora Bell, in the lead role. Furthermore, the casual invitation is not what it seems-he admits to Amory and Milo that Flora has been receiving threatening letters, and he needs their help in finding the mysterious sender. Despite Amory's conflicting feelings, her curiosity gets the better of her, and she begins to make inquiries. It quickly becomes clear that each member of the cast has reason to resent Flora-and with a group so skilled in the art of deception, it isn't easy to separate truth from illusion. When the vague threats escalate, the scene is set for murder, and Amory and Milo must find the killer before the final curtain falls.