Plot summary

Anton Tobias is an average lazy stoner teenager. He has two caring parents (Fred Willard and Connie Ray) and two best friends, Pnub (Elden Henson) and Mick (Seth Green). He has a crush on Molly (Jessica Alba), the girl across the street. Everything is going fine until a string of murders plagues the town. Then, when Anton's parents wind up dead on Halloween, all the clues point to Anton. Anton's hand stabs Mick's forehead with a bottle (killing him), and throws a circular saw blade at Pnub (beheading him). He then realises that his right hand has become possessed (little does he know, the hand is searching for a soul to bring back to Hell). Anton's hand throws his cat across the street after fighting for the remote, and while searching for his cat, his hand forces him to ring Molly's doorbell and the two start a relationship. Anton holds a funeral (of sorts) for his parents and friends. However, Pnub and Mick decide not to go to heaven, claiming the entrance was "too far", and instead return to their former bodies, (although Mick has a bottle in his head and Pnub is still decapitated). With their help Anton must stop his possessed hand.Meanwhile, a druidic high priestess named Debi LeCure (Vivica A. Fox) in Utah has found out that when the locations of killings that have happened all over the country are connected in the order they happened, it makes a pentagram. After his hand kills two cops Anton knew from high school, Anton cuts it off with a cleaver and Mick cauterizes his wound with an iron. Pnub and Mick go to his place for a First-Aid Kit as Anton battles with his severed hand, eventually trapping it in a microwave and burning it. Meanwhile, Debi (now along with Randy (Jack Noseworthy), a local metalhead with a monster truck and a neighbor of Anton) hunts Anton down, as Debi knows how to put a stop to Anton's possessed hand. After sending Molly to the school dance, to what Anton thinks will be a safe place, Anton returns to his home to finish off the hand. Unfortunately Pnub and Mick opened the microwave to make some burritos and the hand had already escaped. Mick fixes Pnub's decapitated head with a meat fork and duct tape and they head to the dance with Anton to look for the hand.The three steal Randy's Ford, accidentally hitting Debi while backing up, and knocking her unconscious. Randy uses "CPR" on her and revives her. Meanwhile, a couple making out in a car are killed, one's neck being broken, the other's head bashed in. Anton, Pnub, and Mick see this and split up. Mick and Pnub go to the school Halloween dance (everyone thinks their gory appearance is a costume) to watch over Molly, while Anton looks for the hand. The hand, meanwhile, kills the principal in his office while he indulges in a little phone sex. Randy and Debi meet up with Anton, and after attempting to kill him to "stop the evil", they realize he has cut off his hand, and it is loose somewhere in the building, Debi explains to Anton that the hand will drag Molly's soul into the netherworld with it at 12:00am Druid time, which is in 6 minutes. Pnub and Mick, meanwhile, are at the dance 'watching' over Molly. Anton tries to warn everyone about his hand, but is just booed at for stopping the show.The Hand then kills the lead singer (Dexter Holland of The Offspring) at the dance and causes a panic. Molly and her friend Tanya, however, escape through the vents. They end up at a giant fan, and Molly uses Tanya's shoe to stop the fan from moving. Molly climbs down using a rope, but Tanya is too afraid to go, so she stalls; and the hand comes and ties the rope around her neck, then shoves her down. Then the Hand removes Tanya's shoe, causing the rope to pull Tanya into the now moving fan. Molly runs into the art room, only to have a pot smashed on her head by the hand, knocking her out. Anton, now searching in the art room, fights with the Hand while it is inside a puppet; but as soon as he is about to finish it off, Mick and Pnub drop from the vents right on top of him, causing it to escape. They hear Molly scream, and find the Hand in an autoshop, with Molly strapped to a car being raised toward a pentagram on the ceiling. Anton, Mick & Pnub fight with the Hand over the controls to try stop the car, but the Hand has a good grip. Mick finds a mechanics "Mighty Joe Bong" and he and Pnub smoke a bowl "for strength" while Molly is raised toward the roof. Anton takes in some and blows his smoke into the Hand (which is still inside a hand-puppet) getting it stoned, where it drops the controls and they save Molly. Debi throws a ritual knife into the Hand (which lands in Mick's chest), stopping it in a puff of smoke and fire. She and Randy take off for "ritualistic sex." Anton releases Molly from the top of the car, they go under the car and start making out. Meanwhile, Mick realizes he never got a hit off of the mechanics 3-Chamber Bong, and tells Pnub to 'light me up'. In the process of lighting the Bong, Pnub accidentally hits the controls for the car, and Anton is crushed by the car when the controls lower it too fast.In the film's climax, Anton and Molly went into the hospital. Anton has given up heaven to stay with Molly, and Mick and Pnub are now his Guardian Angels, sent to see that he does not return to his "evil ways". After Molly leaves, Mick and Pnub go to the SnackMaster in the hall, shutting off the lights as they leave the room. Anton looks at the ceiling to see "I'M UNDER THE BED" written in glow-in-the-dark paint. As Anton screams for Mick and Pnub, the two joke about how they wrote the sign and how Anton screams like a girl.