Jennifer, Jennifer, flees Australia and takes a nanny job in the Netherlands, hoping for a quiet life. But her past catches up with her when her new employers begin to suspect she is a fugitive, forcing her to improvise in order to stay hidden.
Desperate to slip away from Amsterdam and disappear into the crowd, she tries to bluff her way onto a tour bus. The driver, Abe, lets her board without a ticket, joking that “> there’s always room for another sinner.” The bus becomes a strange traveling room, filled with a mismatched group: Douglas the British businessman and his son, Curt; Jackson, a British soldier burdened by a troubling past; Ruby, a French photographer sent to capture windmills; Takashi, a university student who speaks only Japanese; and Nicholas, a troubled British physician.
Takashi notices something unsettling about [Ruby], recognizing her as the star of a well-known Japanese advertising campaign. Ruby, trying to play it cool, asks him not to create a scene, and the moment passes as Jennifer accidentally drops a pill bottle. Nicholas examines the label and returns it to her, while she insists that they worry about real issues, not her supposed instability. When Jennifer swerves to claim that the bus hit a man in the road—a vision of her dead father appears—tension rises, and the group grows wary of her. The bus won’t restart, Abe proposes waiting for help, and the mood grows tense as suspicions and nerves fray.
Abe and Jennifer step away to investigate a nearby windmill, leaving the rest behind. Jackson, under the weight of his own trauma, experiences a nightmarish encounter when a scythe-wielding demon appears and kills him, while Jennifer barely escapes the same fate. The others refuse to believe Jennifer’s warnings, and Nicholas points out the earlier bottle—an anti-psychotic—hinting that all might not be what it seems. When they finally disembark, Curt is accidentally injured, and Douglas lamels that Jennifer is to blame, insisting his son’s life could be at risk because of her presence.
Seeking help, Abe leads the group to an abandoned cabin and, against Jennifer’s objections, departs to find the miller who might be able to assist them. Meanwhile, Takashi, separated from the group for a moment, encounters a ghostly grandmother and speaks with regret about leaving her behind. Back at the cabin, the party discovers an ancient document telling of a local Devil-worshipping miller who was burned alive and later returned as a vengeful demon. Each traveler uncovers personal items that echo dark secrets, triggering nightmares and flashbacks. Jennifer finally admits that she unintentionally caused her younger brother’s death while trying to protect her family from their abusive father.
As the group confronts the truth about themselves, Nicholas steps outside and curses a silent, spectral patient that ruined his career—only to reveal that he had been drunk while operating on Jennifer, contributing to her death in the past. Takashi returns and witnesses the demon kill Nicholas, a moment that hardens the group’s fear and shifts their focus toward Jennifer’s guilt and the demon’s malevolent purpose. The demon spares Takashi after hearing him acknowledge his remorse, a detail that unsettles the others and deepens the sense of fate surrounding Jennifer.
Confessions erupt: Ruby admits she once hired a yakuza to disfigure a rival model in Japan, and Douglas confesses to killing his wife. Ruby’s pride quickly turns to horror as she drowns after admiring her reflection in a pool of water, and the demonic miller decapitates Douglas. Revealed as the miller’s assistant, Abe reveals his role and kills Takashi to prevent the miller from harming the innocent or the remorseful. He lures Curt and Jennifer back to the windmill under the pretense of helping them set it on fire. Jennifer shows no remorse for her past actions toward her father, and the miller attacks her. Curt escapes and, in a desperate move, sets the windmill ablaze. As the miller vanishes, Jennifer remembers her dead brother and rushes to save Curt, cutting Abe’s neck in a final, brutal clash.
Abe, mortally wounded, survives by using bone meal from the mill to staunch the bleeding. The miller reappears, taunting Jennifer with the notion that she cannot escape her fate, and then kills her in front of Curt, sealing a grim cycle of retribution. In the aftermath, Abe salvages another busload of travelers and, when one passenger cannot pay, allows them aboard, repeating the same line from earlier and ensuring the eerie, unsettling continuation of the nightmare.
