Identical twin brothers Elliot and Beverly Mantle are brilliant, highly successful gynecologists sharing everything from a cutting-edge fertility clinic to their apartment and, historically, their romantic partners. Elliot, the confident and charismatic extrovert, initiates romantic conquests with wealthy, complex women, but when he grows tired of them, he secretly passes them on to Beverly, the more sensitive, socially awkward, and emotionally vulnerable twin. Neither woman ever suspects the deception, bonded as the brothers are by an eerie, symbiotic codependency.The status quo shatters when famous, alluring actress Claire Niveau enters their clinic seeking treatment for infertility. Elliot immediately seduces her, but as the relationship deepens, he hands her over to Beverly per their usual routine. However, unlike past women, Beverly falls deeply and obsessively in love with Claire, and she soon reciprocates these intense feelings, recognizing a unique depth in Beverly that she missed in Elliot.This unexpected emotional attachment triggers a destructive
downward spiral. Claire discovers the twins' bizarre deception, leading to a temporary rift, but she ultimately forgives Beverly. Yet, the revelation fractures the brothers' psychological equilibrium. Beverly, desperate to hold onto Claire and increasingly tormented by the fear of losing his individuality, descends into severe drug addiction and psychological instability. Elliot, equally panicked by the breakdown of their lifelong bond and shared identity, begins mirroring Beverly’s heavy barbiturate use in a misguided attempt to remain psychically linked to his brother.Their professional lives crumble as the once-revered surgeons begin performing erratic, drug-fueled gynecological procedures using bizarre, terrifying surgical instruments designed by Beverly for "mutant women." Following a disastrous
public meltdown at a medical convention where Beverly rants about abnormal anatomy, the clinic is effectively ruined, and Claire flees to escape their suffocating, destructive orbit.Isolated in their luxurious apartment, now transformed into a claustrophobic wasteland of filth, syringes, and paranoia, the twins attempt a final, desperate equalization. Convinced they are biologically and spiritually inseparable, Beverly forces Elliot into a bizarre, fatal surgical ritual. In the grim climax, Beverly uses one of his custom instruments to perform surgery on his brother, intending to separate them once and for all, only to realize the horrifying permanence of what he has done. Left utterly alone in the quiet aftermath, Beverly surrenders to his fate, embracing a tragic end that proves their lifelong belief: they could never truly exist apart.