Harry, a film student, receives the sad news that his father has passed away. On his mother's request, he returns to his childhood home, the quiet hamlet of Haast, to attend his father's funeral. Harry brings his childhood friend Luke along for support.
Upon arriving in the small town, Harry learns his mother has already remarried, to none other than her own brother-in-law, Harry's uncle Charles. Harry is of course furious. His first night in Haast, Harry is visited by the terrifying ghost of his father. The ghost tells Harry that Charles killed him to get to his wife, and demands Harry seek vengeance immediately. Harry begins to plot his uncle's murder.
Apparently driven mad by the appearance of the ghost, his grief for his father and fury at his mother, Harry begins displaying psychopathic behavior, attacking Charles with a cleaver. Charles defends himself without injury, before giving Paul, Luke's father, the task of keeping an eye on Harry while the boys are in Haast.
Julie, Luke's sister and Harry's childhood girlfriend confronts Harry about his psychosis. Harry insists that he's just acting, to provoke a confession of murder out of Charles. Harry invites everyone to watch a film he's been working on, in which a man kills his brother. He observes Charles closely during the screening to try and judge his guilt, to no avail.
That night, Harry finds a man spying on him, and attacks him in the darkness, presuming it to be Charles. Upon realizing he has instead brutally murdered Paul, Harry goes into hiding. Soon after, Julie's body is found, drowned. Blame is cast on Harry due to his psychotic behavior. Charles convinces Luke to find Harry, and to bring him back to face the consequences of his actions, hoping that Luke kills Harry in an act of revenge.
Luke finds Harry in the cemetery, mourning at Julie's grave. Luke attacks Harry with a spade and the pair fight furiously but neither is killed. Luke convinces Harry to return home to resolve this madness. Charles invites everyone to a dinner, hoping to kill Harry, but Harry has his own bloody plans for the evening. As our story ends, it remains ambiguous whether Harry was indeed mad or just acting to provoke Charles. Also ambiguous is the nature of the ghost: was it Harry's grief stricken imagination, the spirit of his father, or the devil himself provoking chaos in the quiet hamlet?