Helen and her 12-year-old daughter, Lilly, are driving to the desert for some time away from Hollywood. After squashing a rattlesnake under her wheels, another Rattler manages to slither into Helen's car and her. Distracted by the painful bite, Helen crashes her car into a ditch. Stranded in the desert with no phone and water, Helen and Lilly go on a desperate search for a doctor and safety. Yet, wherever they go, the Rattler follows quickly behind. With Helen's body growing weaker and slower, it makes it easier for the clever snake to attack. But why is the snake following them, hunting them and ready to kill? And why is the Rattler not the only enemy who is after the two?