Beverly and Elliot Mantle (Jeremy Irons) are twin brothers who share everything; the same job as gynecologists, the same house, and even the same women. Beverly is more confident than his twin in all things. When it comes to women, when he tires of one, he simply passes her off to his less assertive brother without the woman knowing the difference. One day their practice is visited by an alluring actress, Claire Niveau (Genevieve Bujold). As she begins to fall in love, is it with Beverly? Or is it that she loves Elliot? There is no certainty because Beverly and Elliot's mannerisms are so similar. As Elliot begins to fall for Claire, the whole co-dependency on the brothers leads to questions about individual identity. As the twins' relationships with Claire begin to hamper their brotherhood, Elliot and Beverly conspire against each other and begin to devolve into mind games, madness and ultimately murder.