Lili convinces her boyfriend Alex to participate in a rather special swinger evening... invitation only and orchestrated by a bourgeois couple, the nave young lovers are in for an unforgettable night. At this party, couples put their keys into a basin, and in turn each pick one out in the chance to enjoy a night with someone else. This new thrilling opportunity to exchange partners, gives Lili hope in spicing up her sex life with Alex. However during this tantalizing night, where fantasies become reality, the strength of the couple's relationship is put to the test... and nothing will ever be the same.