Amsterdam, Present Day - Mr. de Vries finds himself in a treacherous situation when he realizes that his seemingly innocent Australian nanny, Julie, is actually the fugitive Jennifer Harris. In an unexpected turn of events, Jennifer strikes him with a vase and makes a swift escape.
As fate would have it, Jennifer hides aboard a countryside tour bus filled with an eclectic group: the young boy Curt and his preoccupied businessman father Douglas West, a drug-addicted doctor Nicholas Cooper, the former model turned ambitious French photographer Ruby Rousseau, a hungover soldier named Jackson, and a Japanese tourist, Takashi Kido, who is in Holland to pay tribute to his late grandmother. The bus is driven by Abe, who is unaware of the chaos about to ensue.
The adventure takes a terrifying twist when Jennifer, believing she sees her deceased father on the road, demands that Abe stop suddenly, causing the bus to stall. Desperate for help, Jennifer and Jackson set off on foot to a nearby windmill. Here, Jackson experiences a haunting flashback of his own—a memory of a violent act committed the night before, which culminates in a shocking encounter with a supernatural figure armed with a scythe.
Jennifer hastily returns to the bus, her frantic recounting of Jackson's plight dismissed by Nicholas, who labels her as delusional. Suddenly, a violent force rocks the bus, leading the terrified passengers to flee just moments before it tips into a stream. In their escape, Curt injures himself, sending his father into a panic, knowing that Curt is a hemophiliac.
The group sets out to find help and encounters an abandoned shack as they search for a miller at the windmill. While Abe heads to the windmill alone, Takashi, guided by the spirit of his family dog, wanders off, only to be haunted by his past actions regarding his grandmother's euthanasia. The mysterious Miller soon appears, brandishing a scythe and deepening the group's sense of dread.
A chilling discovery is made when Abe finds an ancient death warrant for the local miller Hendrik, executed by townsfolk for supposed witchcraft. As Nicholas reveals more about Hendrik's dark legend, he is drawn away by the sight of an unsettling scene—a surgical table in the woods—where his guilt manifests in a terrifying confrontation with the Miller.
Takashi returns to the group and, with Ruby translating, shares his belief that they have become trapped at a gateway to Hell, facing punishment for their sins. Warning that only those who repent can escape, he sheds light on the dire situation they find themselves in. Following this, an alarming sequence of bloody and horrifying events unfolds, as individuals confront their pasts and the consequences that come with them.
As the dark revelations come to light, Jennifer is forced to face her own traumatic past involving her abusive father, while Ruby makes her own admission of guilt. The horrifying Miller collects the debts of their sins in the most gruesome ways.
In a desperate bid for survival, Jennifer and the remaining group members realize that they must set fire to the windmill to seal the gateway. As they gather gasoline, tensions rise and betrayals surface, leading to tragic consequences. Jennifer finds herself against the Miller, who reveals his connection to Abe, leading to a fierce struggle for survival.
Just when it seems they have escaped the clutches of evil, a shocking twist sees the Miller re-emerging from the flames, dragging Jennifer back into the chaos. Meanwhile, young Curt manages to survive, with Abe cementing his role as a harbinger of doom by picking up a new group of individuals—potentially the next victims of the cursed windmill. The cycle of horror continues in this chilling tale of regret, sin, and supernatural retribution.
