The film begins in the vibrant city of Toronto during the year 1954, where we are introduced to the curious young brothers, Elliot and Beverly Mantle, portrayed later by the acclaimed actor Jeremy Irons. As boys, they engage in spirited discussions, exploring the intricacies of sex and their burgeoning understanding of the female form. Fast forward to 1967 where we find the brothers again, now at Cambridge, Massachusetts, earning accolades as brilliant medical professionals in a lab. Their impressive invention, a sophisticated retractor, garners them significant acclaim, but it becomes clear that their lives are intertwined in ways that transcend mere brotherhood; they seemingly share all experiences, including romantic ones.
This duality continues as we leap 21 years into the present, returning once more to Toronto, where Beverly now examines a glamorous movie star, Claire, portrayed by the stunning Geneviève Bujold. Beverly soon discovers that Claire has a curious condition: three openings in her uterus, which captivates his medical interest. This prompts the brothers to regularly switch appointments with their patients. There is a noticeable contrast in their personalities: Elliot is the more daring, vivacious brother, while Beverly leans towards a quieter, more reserved demeanor. Amidst this complexity, Elliot encourages Beverly to pursue Claire, hinting at his own recent liaison with her. This sets the stage for a tug-of-war over affection and intimacy as Beverly becomes enamored with Claire and is reluctant to share this newfound love with Elliot.
Tension mounts as Beverly inadvertently reveals his brother’s existence to Claire, who teasingly suggests he may be schizophrenic. During a lunch with her friend Laura (played by Shirley Douglas), Claire learns of the brothers’ twin status, leading her to confront the unsettling notion that she’s caught in a web of deception with both brothers. When Claire firmly asserts her awareness of the brothers’ duplicity, she decides to leave them both, creating further rifts. Elliot, ever the provocateur, finds amusement in the unfolding drama while Beverly is left dispirited.
As we progress through the story, a pivotal awards ceremony sees Beverly confronting Elliot, fueled by jealousy and alcohol, as he accuses his brother of stealing credit for his discoveries. Although they momentarily patch things up, the tension in their relationship simmers beneath the surface. Beverly, now increasingly dependent on stimulants, continues to drain himself both personally and professionally. In an attempt to apologize to Claire, he finds himself haunted by nightmarish visions in which she tries to tear him from Elliot, further entrenching him in substance abuse.
Elliot’s newfound glamour in his career, highlighted by his reckless encounters with identical twin prostitutes, showcases his reckless abandon. He attempts to sabotage Beverly’s relationship with Claire by showing up on her film set, demanding that she stays only with him and not his brother. This desire for control reveals Elliot’s insecurities and jealousy, but Claire remains resolute, affirming there is a distinct difference between the two brothers.
When Claire departs for business dealings, Beverly succumbs to his spiraling drug use, wrongly suspecting Claire of cheating on him. During a harrowing moment, he concedes to seek help from a metalsmith to create new instruments as his mental stability crumbles. In a critical operation gone wrong, he witnesses the disastrous fallout from both his and Elliot's addictions. As their practice faces dire consequences, they are ultimately forced to shut it down.
Elliot attempts to navigate this dark path but continues to face personal ruin as his lifestyle spirals out of control. A particularly intimate dance with his girlfriend, Cary, placed alongside a fractured Beverly, results in Beverly collapsing due to the overwhelming weight of their shared struggles. This dramatic moment sets into motion Elliot's promise to detoxify Beverly, locking him away in a clinic to help cleanse his system.
As we see the brothers caught in the grips of their dependencies and the chaos of their lives, Claire's return complicates matters further. She clarifies the mix-up about Beverly's condition and attempts to rally him. However, when Beverly struggles to escape the clinic for their meeting, it becomes evident that he is losing grasp on reality. An art exhibit that displays the tools he had created adds an ironic twist to this descent.
In sheer desperation, Beverly returns to the clinic only to discover chaos — their lives have been unmade by their addictions, with Elliot in the shower in disarray. As they agree to attempt recovery, it is a fragile truce filled with childlike vulnerability. In a haunting twist, Beverly, in a drug-fueled daze, operates on Elliot using his custom tools with disastrous results, reflecting the most tragic consequences of their destructive bond.
The film culminates in a chilling climax as Beverly awakens, horrified to find the aftermath of his actions — his brother disemboweled and ultimately leaving Beverly to confront the abyss of their tumultuous relationship. He finds himself lost, making a solitary phone call to Claire but hanging up, unwilling or unable to bridge the final chasm that now separates him from both her and Elliot. In a poignant final moment, he collapses, forever intertwined with the brother that he both loved and was consumed by. The end serves as a harrowing meditation on identity, addiction, and the complex bonds of brotherhood.
