An English couple holiday in Venice to sort out their relationship. There is some friction and distance between them, and we also sense they are being watched. One evening, they lose their way looking for a restaurant, and a stranger invites them to accompany him. He plies them with wine and grotesque stories from his childhood. They leave disoriented, physically ill, and morally repelled. But, next day, when the stranger sees them in the piazza, they accept an invitation to his sumptuous flat. After this visit, the pair find the depth to face questions about each other, only to be drawn back into the mysterious and menacing fantasies of the stranger and his mate.