The film opens with Bobby, one of the survivors from the first film and his psychiatrist discussing when Papa Jupiter tried to kill him and Brenda eight years ago. Bobby is still disturbed by the events in the first film, but he and Rachel (the daughter of Papa Jupiter who betrayed her family, and used to be called Ruby but has changed her name) now own a biker team. Bobby and Ruby have also invented a super fuel that can power bikes, but the team is due to race in the desert where the original massacre took place. Bobby's psychiatrist tries to convince him to go, but Bobby decides against it. Rachel takes his place and the team consisting of the blind Cass, her boyfriend Roy, Harry, Hulk, Foster, Sue and Jane meet up at a bus and set off. Along the way, they pick up Beast, the dog from the first film, who now belongs to Rachel.
Going through the desert, they get lost and Harry suggests a shortcut through the bombing range. As they drive, the bus begins leaking petrol. However, the bus arrives at an old mining ranch in a new area unseen in the first film. As they explore the mine, Pluto, who survived his attack from Beast in the previous film, jumps Rachel. She fends him off though and he retreats. No one believes her at first but then Pluto returns and steals one of their bikes. Roy and Harry give chase although Harry falls behind, gets caught in a trap and is flattened by a massive rock. Roy catches Pluto but is ambushed by a 7-foot cannibal called the Reaper and knocked out, but is still alive. The Reaper is later revealed to be Papa Jupiter's big brother.
Meanwhile, the rest of the group stay at the mine until nightfall, at which time they begin to get worried for Roy and Harry. Rachel and Hulk depart to look for them while the others stay put. The Reaper then begins to stalk the remaining teens. First Hulk, who he shoots through the chest with a spear bolt, leaving Rachel to run around.
The Reaper then returns to the mine, where he pulls Foster under the bus and kills him with a hatchet. Jane finds Foster's body but the Reaper catches her and crushes her in a bearhug. Sue returned to the camp only to be thrown on a window by the Reaper and then getting her throat slit with a machete. Rachel then stumbled on the grass. She briefly runs into Pluto, but Beast surprises him and chases him away. She then runs into the Reaper again, here he pushes her and hits her head on a rock killing her, leaving only Cass.
Meanwhile, Roy wakes up and runs into Pluto at the top of a cliff. Pluto gets ready to attack Roy but Beast returns and knocks him off the cliff, killing him.
Cass runs from the Reaper and ends up in his mineshaft where he dumped the bodies.There she comes across the corpses of her friends and the grissly remains of Harry. She throws a jar of acid at his face and escapes up a rope with help from Roy. The Reaper follows them but they trap him in the bus where all the bike fuel is. They set it on fire and watch as it blows up. The Reaper escapes from the wreckage with flames all over his body and tries one more time to kill them but stumbles down into an open mineshaft, leading to his death.
Roy, Cass, and Beast walk away from the mine into the vast desert and follow the road home.