Ariane lives with wealthy Simon in the Paris apartment he shares with his grandmother. Constantly suspecting Ariane of infidelity, Simon arranges for her friend Andree to chaperone her whenever she leaves the apartment. Sympathetic and even affectionate to Simon, Ariane prefers women as sexual partners, and she leads a (known) double life, thus intensifying Simon's obsession and desire. But when the jealousy becomes overwhelming Simon asks Ariane to leave, causing a painful break-up which proves fatal.