We are introduced to the Smith family—a quintessentially British clan about to swap city life for a coastal holiday. Father Richard, mother Susan, sister Jessie, and brother Sam appear to be a typical modern family, with the teenagers rubbing against their parents’ more measured pace. Their plan to catch a ferry to a remote island starts to feel off almost as soon as they arrive at the seaside restaurant, where the locals’ reactions run from wary to unnatural. The restaurateur and his wife warn them that the island is “forbidden” during Karantan, a superstition that is echoed by the ferry conductor and the ferry’s passengers, who stare with something more than ordinary curiosity.
When the Smiths disembark, the shoreline greets them with an uneasy silence—the kind that signals that things on the island are not as welcoming as they seem. The islanders, led by the stern elder Klara, make it clear that outsiders are not welcome. Susan’s curiosity is piqued by a buried family history—an ancestor who fought in a brutal massacre that one of Karantan’s stories claims as its center—and she wonders what truth might lie behind the island’s strict rules. Yet the locals’ hostility remains, and the family’s attempt to stay and understand what’s happening is met with mounting tension.
The plot thickens when Mats Larsson [Eero Milonoff], the owner of the bed-and-breakfast where the Smiths are staying, steps forward to invite them into the house. Mats’s warmth feels calculated, and his behavior oscillates between cordial and unsettling. The interior of the cottage is cozy and inviting, a stark contrast to Mats’s odd, almost obsessive demeanor—especially around Jessie. As Jessie begins to sense that she’s being watched, even during a private moment in her room, a sense of claustrophobic danger settles in.
That night, ominous signs intensify. Torches flare outside their home, and the Smiths discover the islanders’ troubling habit of gathering at their courtyard and leaving a chilling foreboding scene—an animal’s carcass on the doorstep that stirs fear and confusion in the family. Richard’s guarded calm and Susan’s suspicions reveal a marriage under strain, with hints of hidden experiences from Richard’s past that surface as the day’s quiet unease grows.
The islanders’ vigilance grows sharper as the Smiths explore the area. Richard and Susan notice boats from the mainland carrying coffins, a disturbing reminder that death and ritual are never far from the surface here. Jessie and Sam, too, encounter the locals’ strange hospitality—mask-wearing figures and coffins marked with ominous hints—before being pushed to leave the breakfast room. The siblings’ reactions are more defiant than their parents’, a small strand of resistance in a setting designed to break outsiders down.
A chilling moment unfolds when Jessie discovers a personal item out of place and a hidden danger behind a full-length mirror in her room, hinting at Mats’s secret life and his invasive interest in her. The elder Klara remains relentless, pressing on with a ritualistic fervor that she believes will secure the community’s future, even as younger members show signs of reluctance.
As the Karantan ritual advances, Mats is drawn deeper into the scheme. He uses a scheme involving drugged biscuits to entice the guests, seeking to satisfy a perverse appetite in exchange for delivering bodies to the community for feasting. The Smiths’ true nature is revealed in a shocking twist: they are not ordinary vacationers but a family with a history of killing, who have come to enact what they call a “slaycation.”
The chilling premise—Britain’s ostensibly ordinary family reveals itself as serial killers—unfolds with brutal clarity. The earlier hints of violence, including the restaurant beheading of a swan and a past murder by Richard, align with the present carnage as the Smiths begin to turn on the islanders with ruthless efficiency. As the islanders push back, the family’s plan to remain undetected begins to crumble. Sam and Jessie play key roles in resisting the locals and confronting the broader conspiracy at the heart of the island’s traditions.
The confrontation intensifies as Klara’s dogmatic grip on the community collides with the Smiths’ predatory pragmatism. The Smiths, in turn, uncover the island’s surveillance setup and a hidden tunnel, which give them a tactical edge in their deadly game. In a climactic turn, police involvement arrives via a mainland detective who misreads the situation, seeing the islanders as aggressors while the Smiths’ violent spree continues to unfold. The detective’s arrival barely postpones the inevitable.
In the final act, the Smiths escape into a rough, bloody relief—though not without cost. A brutal standoff leaves one of the siblings gravely wounded, and the truth about Sam’s role—revealed as a hired killer—casts a new light on the group’s dynamics and Richard’s erratic, explosive temper. Klara’s last attempt to salvage control ends in a shocking confrontation with the law, as she is shot by the police inspector, who has been chasing the truth behind the killings.
The story closes on a paradoxical note: the Smith family is alive, albeit battered and scarred, and they depart the island by speedboat with a grim, almost delirious satisfaction. What begins as a misfit holiday becomes a savage, if darkly comic, meditation on family, ritual, and the lure of violence. The island’s strange, deadly customs collide with a family’s long-buried impulses, producing a tonal blend of suspense and teeth-clenching dark humor that lingers long after the credits roll.
