Attractive, blonde Sarah lives happily with her husband in a state of suburban bliss. Until she receives a salacious e-mail from a man called 'Brian', who knows intimate details about her. It suggests she is being watched. More mails arrive admiring her sexy outfits. Her bemusement soon turns to curiosity and she begins a correspondence with Brian. Convinced the writer is her husband, she begins to follow the requests in the emails and engages in sexual games with her husband. Hooked on the game, the requests become more extreme and she engages in affairs with other men. It is only then that she becomes aware that the identity behind Brian is not her husband. A stranger has transformed her from a loyal loving wife, to an insatiable adulterer.

Swamped by an overwhelming desire not only to discover who Brian is, but to find gratification from outrageous sexual acts, she begins to seduce the men she suspects are Brian. Time after time she attempts to solve the mystery of Brian, but fails, while slipping further and further into shame and depravity. And all the time, he watches, until ... finally, he is revealed.