After years of tension, Richard (Clive Owen) begins a sexual relationship with his sister Natalie (Saskia Reeves). Now married, their relationship becomes dangerously obsessive. The contrast between their private intensity and the middle-class, inhibited, stuffy public scenes we see in the Richmond world in which Natalie has moved with her marriage is evident. As the guilt and intensity of the siblings increase, we seem to be heading for disaster, a foreboding which increases when Natalie's husband Sinclair finds out.