In 1599 Italy, Beatrice Cenci is the teenage daughter of the crazed landowner and nobleman Francesco Cenci who keeps her locked up in the dungeon of his castle where he sexually abuses her. Beatrice plots with her stepmother, her besotted servant Olimpio, as well as a local bandit, named Catalano to plan Francesco’s murder.
Having casually overheard a confusing phone conversation between two women, Alberto manages to get in touch with one of the callers, Claudia, a painter. The two become lovers and things are spiced up by Claudia's ambiguous sexual nature and by the presence of her former lover, Pietro. Alberto discovers a pistol in Claudia's handbag and this leads to a further revelation: she's dominated by her stepmother Greta, who forced her into a clandestine lesbian relationship; of which Claudia is ashamed and wants to end - at all costs. Alberto, now a slave to love, runs Greta over. But Claudia denies urging him to murder...
