A young Tommy Jarvis stumbles upon a graveyard while walking through the woods on a rainy night, where he witnesses two grave robbers digging up the corpse of Jason Voorhees. Jason rises from the grave and murders the two graverobbers before advancing towards Tommy.
Awakening from his nightmare, an adult Tommy is delivered to Pinehurst; a Halfway House in which he can hope to acclimate to a normal life. The director Pam introduces Tommy to the head doctor Matt, and up in his assigned room, he meets Reggie, a boy who is visiting his grandfather George who works in the kitchen.
Other teens introduced are Robyn, goth Violet, shy Jake, attitude-ridden Vic and compulsive eater Joey. The sheriff brings two more residents; Tina and Eddie after catching them having sex on the neighbor Ethel Hubbard's lawn. The Hubbards show up moments later and threaten to have the "loony bin" closed down.
Afterward, Vic and Joey get in a minor altercation, which results in Vic slaughtering Joey with an axe and he is subsequently arrested. Attending ambulance drivers Duke and Roy Burns discover the body and Roy is devastated by angered by the light nature Duke makes of the murder.
That night, two teens stranded by the road are killed when an unseen killer shoves a road flare into Vinnie's mouth, then slashes Pete's throat with a machete. The following night, hospital orderly Billy is killed with an axe to the skull while his girlfriend Lana is killed with an axe to the stomach.
Panic begins to ensue, but the mayor refuses the sheriff's claim that somehow Jason Voorhees has returned. Meanwhile, Tommy experiences hallucinations of Jason (in his regular hockey mask) when he takes his medicine while Tina and Eddie run off to have sex. Ethel's temporary farmhand is murdered watching the teens have sex, then Tina's eyes are gouged out by a pair of shears while Eddie is away for a moment.
He returns to discover her, and is killed by Jason when his skull is crushed against a tree with a belt. At the house, George gives Reggie permission to visit his visiting brother Demon, and Matt convinces Pam to take Tommy with them. While there, Junior instigates fight with Tommy, and he runs off when Pam tries to stop it.
After Reggie and Pam leave, Jason kills Demon and his girlfriend Nita as well. Pam returns Reggie to the house and they say that Matt and George left to find Tina and Eddie who hadn't returned and Pam leaves to find everyone. At the Hubbard farm, Junior is decapitated riding his bike angrily in the yard and Ethel is slashed in the face with a knife, and left to drown in her stew.
While watching a movie, Jake confesses his attraction to Robyn who laughs at him and he storms off, only to be killed by a cleaver to his face. Later, Robyn goes to bed and discovers Jake's body before she is brutally stabbed from under her bed. Jason moves into Vi's room and stabs her through the stomach while she is dancing to music.
Reggie awakens and discovers their bodies in Tommy's room before running into Pam. Jason bursts into the house and chases them out into the rain, after discovering Duke's dead body they double back and Pam finds Matt, dead with a spike through his skull. She returns to the house and George, whose eyes had been gouged out is thrown through a window at her.
She rushes toward the barn, chased by Jason, but he is struck by a tractor driven by Reggie. They run into the barn and hide as Jason comes to find them. Tommy comes shortly after and believes Jason to be a hallucination until he is attacked by him. Together they manage to trick Jason into falling out of the loft window and he is killed on a harrow below, his masks torn, revealing that he was Roy Burns all along.
At the hospital, the sheriff tells Pam that Joey was Roy's son, and after seeing him slaughtered adopted Jason's M.O. to kill everyone at the house. She goes to Tommy's room who awakens and stabs her with a hidden machete before Tommy awakens to a hallucination of Jason.
Facing his fears, he makes Jason's illusion disappear. He hears Pam approaching and throws his bed through the window to make it look like he's escaped. When she rushes in, he appears from behind the door, wearing Jason's hockey mask and holding a knife as the screen goes to white.