After years of marriage, Joy (Toni Collette) and Alan Richards (Steven Mackintosh) find themselves in a sexual rut. Therapist Joy is trying to find a way to keep her spark with her husband, following a cycling accident which has put their sex life on hold. Suddenly Joy and Alan find themselves drawn to new people, and both are tempted to make the ultimate indiscretion. With their marriage in crisis Joy comes up with an audacious, unorthodox, but potentially brilliant proposal that will have huge ramifications for the future...