The movie commences with Evan, a young man grappling with the loss of his mother, as he shares a meal with his solitary friend. This dinner takes an unexpected turn when he overhears a heated dispute between a man and his female companion. Disturbed by the altercation, Evan decides to cut his conversation short and return to work at the restaurant. There, he is confronted by the very man from the argument, who, in an inebriated rage, attacks him. In a moment of self-defense, Evan retaliates violently, ultimately losing his job as a consequence. Despite his desperate pleas to retain his position, the management remains unsympathetic, though a sympathetic co-worker pledges to advocate on his behalf.
On his way back home, Evan soon realizes he is being followed by the man's friends, who ominously inform him they know his address. Fearful of retribution, potential lawsuits, and with no job or family left to anchor him, Evan contemplates fleeing the city. His friend suggests he spend the night with a woman, and although hesitant at first, he ends up sleeping with an unnamed girl that evening. The following morning reveals the stark reality of their encounter when the girl leaves abruptly after realizing Evan harbors no romantic feelings.
As Evan sinks deeper into a state of drunkenness, the sound of knocking on his door wakes him, and through the window, he sees the police arriving, convinced he is not home. Seizing the opportunity, he hastily books a last-minute flight to Italy. Upon his arrival, he finds himself enveloped in carefree camaraderie as he shares drinks and indulgences with some locals. Life seems to smile upon him as he enjoys the stunning Italian landscape while road-tripping with his newfound companions.
During his travels, Evan encounters a mesmerizing young woman named Louise, who reciprocates his fascination. A chance meeting at a bar leads to an immediate chemistry between them, prompting Evan to invite her out the next night. When his friends hint at leaving, he chooses to stay behind, longing for a second chance to see Louise. Evan soon seeks work on a nearby farm, where he bonds with the farmer, Angelo, and arranges another outing with Louise, who initially had declined his invitation.
Their date takes them to an art museum where Evan learns about Louise's passion for art and her extensive travels, including relationships with other men that have all ended in disappointment. Their connection deepens over a dinner filled with conversation, revealing her struggle with faith and her intriguing personality. Delighted, Evan writes a playful love letter at her behest, which she receives with unexpected warmth.
As their relationship blossoms and they enjoy each other's company, a night of passion leads to complications—Louise reveals a shocking secret about her true nature. As she transforms into a monstrous figure, she takes medication to suppress this condition. They navigate their complex feelings for each other, but Evan is disturbed by glimpses of Louise's grotesque transformation.
Simultaneously, Evan faces his own turmoil from a past marked by tragedy—the recent death of both his parents. Their candid discussions about loss and identity become a foundation for their relationship, even as Louise’s condition worsens. Each painful transformation she undergoes pushes them closer to a breaking point, exacerbated by the dark creatures from Evan's nightmares that embody his fears of abandonment.
Faced with her deteriorating condition, Louise performs a ritual in a cave to counteract her mutation, but her struggles only seem to escalate. Interspersed with moments of tenderness, each encounter between them swells with emotional intensity, revealing their vulnerabilities. The heartache intensifies as they grapple with the precarious nature of their relationship.
When confrontations with Angelo reveal the severity of Evan's own predicament—working illegally as an immigrant—he realizes he has few safe places left to turn. After a heated argument with Louise, he hesitates before returning to her, only to confront the full extent of her transformation into a fantastical beast. Their passionate bond, however, refuses to dissolve, even as Evan wrestles with feelings of betrayal when Louise admits her lack of immortality without him.
Their connection reaches a climactic point when faced with immigration authorities, and in an act of defiance, she helps him escape, sending them on a rapid road trip to Pompeii where they open up about their histories and deepest fears. It’s during this journey that Evan implores Louise to consider a life of mortality alongside him, arguing that embracing humanity could be more rewarding than immortality.
In the midst of an emotional conflict heightened by evocations of a monstrous transformation, Evan's steadfast determination to stay by her side leads to an intense confrontation with her fear of her true self. Just as she seems on the verge of losing complete control, a moment of vulnerability gives way to the revelation of her true feelings for him. They face the eruption of a volcano in the distance, symbolizing the breaking point of their relationship, but rather than fear consuming them, hope emerges.
As Louise embraces the emotional upheaval within her, she ultimately stands at a crucial crossroads, choosing between her monstrous legacy and the possibility of love. Their climactic moment hints at a future filled with love—suggesting that despite the horrors and challenges they face, a choice has been made, and Louise opts for humanity, revealing that love can transcend even the darkest transformations.
