A suburban American family is being stalked by a group of psychotic people who live in the desert, far away from civilization.
The film opens with a group of scientists being killed by the mutant, Pluto (Michael Bailey Smith). A few years later, Ethel Carter (Kathleen Quinlan) and her husband, Bob Carter (Ted Levine) are traveling from Cleveland, Ohio to San Diego, California, with their daughter Brenda (Emilie de Ravin), son Bobby (Dan Byrd), eldest daughter Lynn (Vinessa Shaw), her husband Doug Bukowski (Aaron Stanford), their baby Catherine (Maisie Camilleri Preziosi), and the German Shepherds, Beauty and Beast.
They encounter a gas station attendant, Fred (Tom Bower), who fills their car up and tells them of a short-cut. Taking a supposed short-cut, their tires are punctured by a hidden strike strip. Doug and Bob go look for help, and the rest stay behind. Bobby chases a panicked Beauty and finds her mutilated; frightened, he runs, falls and is knocked unconscious. A young female mutant named Ruby (Laura Ortiz) finds him and hides him from her brother Goggle (Ezra Buzzington). Bob, who goes back to the gas station for help, finds the hysterical attendant, Fred, who commits suicide in front of him. In fear, Bob tries to flee, but is attacked by the mutant leader, Papa Jupiter (Billy Drago). He is dragged into the mining caves by Jupiter, Jupiter's eldest son, Lizard (Robert Joy), and Pluto.
When Bobby awakes, he returns to the trailer, not mentioning Beauty's death. Doug returns and the night progresses starting with the family discovering Bob's yelling, all exiting the trailer except the baby and Brenda. They find Bob being burnt alive and frantically try to save him while Pluto, later followed by Lizard, use the distraction to rape Brenda. Lynn returns to the trailer and is greeted by Lizard and Pluto, She is forced to let Lizard drink from her breasts as her baby is held at gunpoint. Ethel returns and is shot and Lynn stabs Lizard in the leg who shoots her in the head. Lizard and Pluto flee with the baby, after attempting to shoot Brenda.
Doug and Bobby return to the trailer and discover the dead bodies of Lynn and Ethel. After this, the mutant Goggle who is watching the Carters is attacked by Beast, who drags his arm with his walkie-talkie still in hand back to the Carters'. The next morning, Doug sets off to rescue Catherine with the dog Beast and finds the abandoned nuclear testing village and is knocked unconscious by Big Mama (Ivana Turchetto) during his search. He escapes an ice box filled with human body parts upon his awakening and continues his search, only to encounter Big Brain (Desmond Askew). Big Brain tells him the story of the mutants. Doug is attacked by Pluto and almost killed, but manages to distract him and kill him.
Doug surprises the mutant Cyst (Gregory Nicotero) outside and kills him, while Big Brain is killed by Beast just as he orders another mutant to kill baby Catherine. Lizard takes a cleaver and prepares to kill Catherine, but finds Ruby has taken Catherine and left a pig in her place; Lizard chases her. Doug follows, wanting to rescue Catherine. At the trailer, Brenda and Bobby prepare a trap to kill Papa Jupiter.
In the hills, Ruby is about to return Catherine to Doug when Lizard attacks. Lizard and Doug fight, ending with Lizard on the ground. Doug turns his back to Lizard, thinking him dead, but is almost shot by him, but Ruby tackles Lizard, plunging them over a cliff. Bobby and Brenda finish Papa Jupiter off who had barely survived their trap and reunite with Doug, Catherine and Beast. As they celebrate their apparent victory, an unknown mutant watches from binoculars in the hills.Source: Wikipedia