Description
A group of scientists, who are testing the radiation levels of the New Mexico desert, are killed by a deformed mutant, Pluto, with a pickaxe.
Retired detective Bob Carter and his wife Ethel are traveling from Cleveland to San Diego through the desert for their wedding anniversary. With them are their German Sheperds, Beauty and Beast, their children, Lynn, Brenda, and Bobby, Lynn's husband, Doug Bukowski, and their baby daughter Catherine. They stop at a gas station where an elderly attendant tells them of a different route through the hills. Not long after taking the supposed short-cut, their tires are punctured by a hidden spike strip. Doug and Bob go look for help, while the rest of the family stays behind. Beauty escapes from the trailer and, when Bobby chases her into the hills, he finds her mutilated corpse. Frightened, he runs and falls off the hill, knocking himself unconscious as a young female mutant Ruby protects him from her brother Goggle. Doug heads towards the interstate and finds a huge crater filled with numerous abandoned cars and other items.
Back at the gas station that night, Bob finds news clippings detailing various disappearances in the area after recent nuclear testings at a mining town by the US government that caused the mutants' deformities. Horrified, he confronts the hysterical attendant who commits suicide inside an outhouse. Bob attempts to flee in an abandoned car but is subdued by the mutant leader Papa Jupiter. After Bobby is found by Brenda, they head back to the trailer until Doug returns, where the former encounters Jupiter and escapes from him. While Bobby confesses his story to the family, Jupiter's sons Pluto and Lizard infiltrate the trailer and Lizard sexually assaults Brenda, who stays with the baby, while using the distraction of immolating Bob to a tree. Bob dies after the family extinguishes the fire. Lynn decides to return to the van where she saw Lizard holding her baby Catherine, horrified by this, she attacks Lizard but gets overpowered in the process. Lizard forces Lynn to breastfeed him until Ethel comes back leading to Lizard shooting both Lynn and Ethel. He then escaped with Jupiter along with Catherine. Doug and Bobby return to discover the carnage while Lynn and Ethel die shortly afterwards. Goggle, who is watching the family from afar, is killed by Beast.
The next morning Doug, along with Beast, set out to rescue Catherine. He comes across an abandoned nuclear testing village through the miner town's cave system and is knocked unconscious by Big Mama. Awakening in an ice box, he escapes and encounters Big Brain who reveals the mutants' origins to him and sends Pluto to attack Doug but the latter manage to gain the upper hand and kills Pluto with his own axe before killing another mutant Cyst. After ordering Lizard to kill Catherine, Big Brain is mauled to death by Beast while Ruby manages to take the baby from Lizard and escapes through the hills. At the trailer, Brenda and Bobby are attacked by Jupiter as the siblings lure him and arrange an explosive trap, which destroys the vehicle along with the mutant.
Doug catches up with Ruby but Lizard attacks them before pursuing Ruby until Doug manages to defeat him with Cyst's shotgun. Ruby then gives Doug his daughter back. Lizard, still alive, aims the shotgun at Doug but Ruby tackles Lizard off a cliff, sending them both falling to their deaths. Bobby and Brenda find Jupiter wounded from their trap as Brenda finish him off with a pickaxe before the siblings are reunited with Doug, Catherine, and Beast. As the survivors of the Carter family embrace, an unknown mutant watches them through binoculars from the hills.
