While driving alone through the barren stretches of the American Southwest, a young man named Jim Halsey comes across a man hitchhiking in the rain and offers him a ride. The hitchhiker, introducing himself as John Ryder, initially seems quiet but quickly reveals his menacing nature when he tries to kill Jim. Terrified, Jim manages to escape his clutches by pushing him out of the moving vehicle but soon discovers that Ryder is relentless, appearing mysteriously to stalk Jim and leaving a trail of murder and chaos in his wake. As Jim reports his terrifying encounter to the authorities, he finds himself becoming inexplicably entangled in Ryder's deadly games, with law enforcement doubting his innocence. Each time Jim thinks he has distanced himself from Ryder, the hitchhiker reemerges, continuing to play his sadistic game of cat and mouse.

With suspicions mounting against him and nowhere to turn, Jim is on the run both from the law and from the relentless killer. Along the way, he meets Nash, a sympathetic waitress who becomes embroiled in the nightmarish events against her will. As they try to navigate the treacherous expanses of highways and desert roads, Ryder continues his psychological torment, leaving devastating clues of his handiwork for authorities to discover. Feeling isolated from those who should be protecting him, Jim faces the discovery that he must confront his pursuer on his own terms. As the miles stretch on, Jim struggles to survive and find a way to put an end to Ryder's terrifying pursuit before it spirals further beyond his control.