Natalie (Saskia Reeves) is trapped in a comfortable but emotionally stagnant marriage to Sinclair (Alan Rickman), a wealthy, older, and highly successful businessman. Seeking deeper connection, Natalie reconnects with her estranged brother, Richard (Clive Owen). Their intense emotional bond evolves into a secret, passionate incestuous affair, creating a web of deception that eventually draws the suspicion of Sinclair and leads to tragic consequences.