Jim Halsey (C. Thomas Howell), a young man delivering a car from Chicago to San Diego, spots a man hitchhiking and gives him a ride. The man, John Ryder (Rutger Hauer), is a brooding, soft spoken man; when Jim passes a stranded car, however, Ryder's personality suddenly shifts. Ryder calmly states that the reason the car is stranded is because he murdered and mutilated the driver, and he intends to do the same to Jim. Ryder produces a switchblade knife and taunts Jim for several moments before Jim realizes Ryder had never put on his seat belt and that the car door was left ajar, so he knocks him out of the car's passenger door.
Relieved, Jim continues on his journey but sees Ryder with a family on vacation. He tries to warn them but loses control of his car and spins off the road. He continues driving and after a while comes across the families car, with blood oozing out the doors. He carries onwards and pulls into an abandoned gas station to use a phone. While there, Ryder corners him in the garage and simply throws Jim's car keys to the ground and leaves. Jim chases after him, but when a sandstorm whips up he sees Ryder hitch a ride from a man in a jeep. Jim continues driving and eventually sees another gas station. While filling up his car, Ryder attempts to run him over, destroying the fuel tanks which spray gas everywhere. As Jim attempts to flee Ryder drops a match, igniting the surround area in a huge fire ball. Jim's car bursts from the flames and speeds away. There is an extended chase sequence; Ryder reveals he wants Jim to kill him, putting an end to his killing spree. Jim retreats to a roadside diner, where he meets a pretty young waitress named Nash (Jennifer Jason Leigh) and calls the police. She then serves him a cheeseburger and french fries; he starts to relax. One of the fries is a severed finger; Jim tries to flee but he is arrested. Ryder had planted his blood covered switch blade in his pocket. Jim is jailed.
He wakes up in his cell to find the door swinging open. When he leaves he discovers all the arresting officers have had their throats cut. He steals a gun and flees. At a gas station Jim holds two officers hostage and tells them to get in their car and drive with him. As they are driving, Jim speaks via radio to the officer in charge of Jim's case. He desperately explains his story but this fails when Ryder kills them as well. Jim contemplates suicide but resolves to keep going. Seeing a stopped bus, he sneaks on and hides in the bathroom. When Nash gets on and knocks on the door, he grabs her and tries to explain his situation. They sit down at the back of the bus and Jim tells his story. A police car then pulls the bus over. Knowing the police know he is on board, Jim gives himself up. When he steps off the two officers tell him he killed their friends and that he'll pay. One officer tells Jim to wipe his wrist. Knowing that once he does he will be shot in what will look like an act of self-defense, Jim refuses. This infuriates the officer and he threatens to shoot Jim anyway. Suddenly Nash appears and hold the two officers hostage. Once they drop their weapons Nash and Jim flee. Ryder has been watching the entire event nearby. While the two flee, Ryder helps them by shooting down a police helicopter, as it is in the way of his objective to kill Jim.
Jim and Nash make out in a roadside motel. Just as things seem to be getting better, Nash is kidnapped by Ryder. When he begins looking for Nash he is grabbed by two police officers who, instead of arresting him, say they "Have a situation". Jim sees a large trailer and a truck with Nash tied up in-between. The police tell Jim that Ryder asked for him specifically and that they cannot shoot him as his foot will slip off the clutch. This will cause the truck to roll forward, ripping Nash in half. Once Jim gets in the truck, Ryder gives him a gun and tells him to kill him. Jim refuses as Nash will die. Ryder, disappointed, presses down the accelerator and Nash's screams can be heard. Ryder is arrested, but the cops cannot find any information on him. No Birth certificate, no bank account, nothing. As Ryder is being transferred to another facility, Jim cannot contain the urge to kill Ryder in revenge for the death of Nash and steals a weapon, a police car and goes after Ryder. As he is driving behind the police escort, the door swings open to reveal Ryder has killed all officers inside. He jumps onto the hood of Jim's car but gets shot off. When he stands up Jim runs him over. He lights a cigarette and breaths a sigh of relief. Ryder slowly gets up behind him and smiles at. Jim guns Ryder down in a hail of bullets. The film ends with Jim in a similar silhouette to Ryder, cast against a blood red sky....