Identical twins Elliot and Beverly Mantle are gynecologists, who jointly operate a highly successful clinical practice in Toronto that specializes in treating fertility problems. Elliot, the more confident and cynical of the two, seduces women who come to the clinic. When he gets tired of them, the women are passed on to the shy and passive Beverly, while the women remain unaware of the substitution. Actress Claire Niveau comes to the clinic for her infertility, where she is found to have a “trifurcated cervix”, meaning she will probably be unable to have children. Elliot seduces Claire and then urges Beverly to have sex with her. Beverly becomes emotionally attached to Claire, upsetting the equilibrium between the twins.