Through her stepsister Claire Clairmont, Myriam Cyr and her future husband Julian Sands come to know Gabriel Byrne as Lord Byron. During the summer of 1816, Byron invites them to stay for a while at Villa Diodati in Switzerland, where they meet Byron’s physician friend, Timothy Spall as Dr. Polidori. On 16 June, while a storm rages outside, the five occupy themselves with a game of hide-and-seek, letting the tension between flirtation, fear, and curiosity simmer beneath the surface. Later in a parlor, Percy Shelley articulates a fascination with science, while Polidori shares his own speculations about sleepwalking and nightmares, drawing a faint line between the rational and the uncanny.
Byron introduces the group to Phantasmagoria, a collection of horror tales he bought in Geneva, and the trio take turns reading aloud excerpts. This shared reading becomes the spark for a late-night séance conducted around a human skull, a moment that unsettles Claire and triggers memories Mary recalls from their childhood—instances of unexplained phenomena where doors slammed and beds shook without a clear cause. After the séance, Claire is coaxed upstairs to rest, leaving the others to interrogate what they’ve just unleashed.
That night, Mary witnesses a shadowy figure outside the window and, when Percy steps away to investigate a barn door’s creak, he encounters something grotesque. Inside the house, Mary confronts Byron in the billiard room about his treatment of Claire, revealing that Claire is pregnant with his child. The exchange becomes heated, and the couple’s argument escalates into a physical confrontation. Later, Byron’s behavior toward Claire grows more intimate, and the group’s fraught alliance cracks under the weight of desire, fear, jealousy, and moral ambiguity.
The tension intensifies as Claire experiences a troubling episode—Byron’s intimate act with her coincides with her miscarriage. While Mary consoles Percy, who has grown increasingly paranoid, a disturbing odor of decay haunts him. A mysterious incident occurs at the foot of the stairs: Polidori appears by the banister, bleeding from a neck wound, claiming he was bitten by a vampire in his room. Byron suspects self-inflicted wounds, while Shelley and Mary wrestle with the possibility that something supernatural has entered their circle. Shelley voices a chilling belief that the group’s collective fear gave birth to something… and Polidori fears damnation for his homosexuality, even contemplating suicide, though Byron intervenes to stop him.
The atmosphere grows more nightmarish when Claire vanishes from her bed and is found by Shelley, whose horror is compounded when Claire’s body seems to metamorphose in astonishing ways. Mary attempts to flee the house but crashes through a glass door in the process. Shelley posits that the presence haunting them feeds on their fear, while Polidori’s difficulty with the group’s moral boundaries adds another layer of dread. A failed attempt to hang himself in the barn marks a turning point, as he witnesses a figure fleeing on horseback.
In a bid to exorcise the fear, Byron and Shelley try to recreate the séance, while Mary questions the possibility of meaning within the supernatural and beyond the limits of atheistic belief. The trio descends to the basement, where Claire lies nude and covered in mud. Byron attempts to proceed with the séance, but Mary refuses. The atmosphere erupts as Mary crushes the skull and lunges at Byron with a shard; Shelley intervenes, pulling them back from violence and turns their attention to a disturbing vision in which Mary imagines her dead son William in a coffin and a miscarriage reappearing as a nightmare. The moment spirals into a chaotic frenzy, and Mary staggers away, only to be stopped by Shelley as dawn returns. By morning, she reappears in the garden with Byron, Shelley, and Claire, their relationships irrevocably altered by what occurred.
In the contemporary era, tourists visit the Villa, and a voice-over lays out the grim fates of that fateful night: Mary’s son William died three years later, followed by Shelley's drowning in 1822, and Byron’s death two years after that, with Polidori’s suicide in London. Out of Mary’s prior miscarriage arose the fierce impulse to resurrect her child in literature, giving birth to Frankenstein. From Polidori’s tangled feelings and fascination with vampires emerged The Vampyre, a legacy born from the shadows of that single, revelatory night. The film threads together life, love, fear, and creativity, showing how a moment of fear and imagination at a Swiss villa would echo through centuries of storytelling.
