Fifteen years after Jim Halsey's (C. Thomas Howell) horror filled trip through Texas at the mercy of a crazed murderer, he works as a police officer, but has recently been suspended for using excessive force on a kidnapping suspect. It is revealed his girlfriend, Maggie (Kari Wuhrer), has her own crop dusting business. Jim makes a call to retired Captain Estridge in Texas, who asks Jim to come down to Texas to talk to him face to face about his mental scars from the last movie. Maggie, who obviously does not know about the event, pleads with Jim to let her tag along.
Arriving in Texas, the couple pick up a car that Estridge has left for them, and set off to his house. Jim notices a sign along the highway announcing DANGER: DO NOT PICK UP HITCHHIKERS which sets him into flashback mode. The two see an RV that has run off the road, with blood dripping through the door. Maggie wants to stop and help, but Jim speeds up, irritating her and making her more curious about his erratic behavior. Soon, a motorcycle speeds past them and wrecks. Maggie lets the driver into the back, against Jim's understandable protests. The hitcher (Jake Busey) reveals his name to be 'Jim', and after Maggie tells him her occupation he remarks "A farm girl!" He asks them what they are in Texas for, and Jim responds with "None of your damn business." The Hitcher doesn't appear fazed by Jim's impolite behavior. Jim suddenly envision himself and Maggie being killed by the Hitcher, and pulls a gun on him and evicts him from the car. As they speed away, Jim informs Maggie of his last experiences with hitchers, while the Hitcher lights a cigarette and says to no one in particular, "Damn fool." An 18 wheeler stops behind him, and the Hitcher presumably steals it.
Jim and Maggie continue to Estridge's home, but are pulled over by a cop (Steve Railsback) The same 18 wheeler, however, pulls up. The driver steps out, and appears to be the same driver as earlier. The cop says something to the effect of, "Earl, I'm on business here," to which the unseen driver replies, "Well hell, so am I!" and promptly shoots the cop with a revolver. The man slides his 'hair' off his head, and we can see it to be the Hitcher, who scalped the driver and wore his hair as a disguise. Jim and Maggie get into the car. The Hitcher tries to grab Maggie and is dragged by the car before being forced out.
The couple then arrive at the Estridge residence late at night. They find Mrs. Estridge dead in the house, and then go to investigate the barn, finding the captain dead in there. Cops suddenly swarm the residence, including what appears to be the newest sheriff. Jim and Maggie discover the Hitcher in the hayloft of the barn, but can't do much about it, since the Hitcher has a rifle and they don't. The Hitcher fires a few shots at Maggie, but hits Jim when he pushes her out the way. The Hitcher picks off several officers, causing a hail of bullets to be fired on Jim and Maggie. Maggie drags Jim into a truck inside the barn. She drives off with him, evading the cops and the Hitcher. Jim tells her to kill him ASAP, no matter what he says, and dies.
Maggie falls asleep in the desert. When she wakes up she is attacked by the Hitcher and knocked unconscious. She then wakes up inside an abandoned water tower with the Hitcher leering down at her. He tells her to look out, the tower isn't very sturdy, and leaves. Maggie escapes as the tower collapses, and takes the 18-wheeler truck that the Hitcher stole earlier to a remote gas station. She goes in, finding a live clerk. After making a phone call and using a water pump out back to clean up she returns to find her dead. She picks up a souvenir Tomahawk, sees another dead clerk, and the Hitcher in the clerk's uniform. He acts uniformly normal, taunting her. She asks him why he's doing this, and he responds, "Sometimes you just get bored of watching television." Taking the tomahawk from Maggie he then cuts off his finger with the intention of blaming Maggie when the cops arrive.
The cops arrive again, and the Hitcher fires at them with a shotgun. He is grabbed by the cops, as is Maggie as she pursues him. At the police station, the Hitcher concocts a fake story that Maggie all by herself killed the clerks and cops and cut off his finger. He calls himself 'Jack', rather than Jim, which convinces Maggie he could be same man as 15 years before. Maggie is being transported to jail as the sheriff begins to have doubts about her guilt.
While Maggie is being transported to jail the van is struck and knocked on its side by an excavator which the hitcher jumps out of. Jack the Hitcher then takes a gun from the deputy and shoots and kills the deputy in the driver seat before going to the back and shooting and killing the two remaining cops in the van then frees Maggie from the van by taking the cuff key from one of the deputy's and tossing it to her then throwing the revolver to her to make it appear that she killed all the policemen. Then the sheriff shows up and sees the bodies around Maggie as she emerges from the van with a gun and tries talking Maggie down thinking she shot and killed the cops, but is then shot by the Hitcher who then gets into a pickup truck. Maggie takes several bad shots at him, and he gets away. Realizing now that there is no way to prove her innocence, Maggie finally becomes aware that the only way to end all this is to kill Jack the Hitcher before the police find and brutally kill her.
The murderous Hitcher later pulls up to a tanker truck parked along the side of the road kills the driver and takes the tanker truck. Maggie steals a crop duster plane from a nearby airfield, then goes after Jack. They exchange gunfire, air to ground style, before Maggie kamikazes the plane into the truck. She escapes the fireball, as does the truck, which grinds to a halt. She approaches it and finds an unconscious Jack. She ties him up to the truck, (much like the character of Nash in the first movie). Jack the Hitcher wakes up and pleads not to kill him because he claims not to be the same person, but Maggie cares little, and places a bag of feed on the clutch, ripping it open with a knife, slowly causing the truck to roll forward.
However, the police show up again when a single squad car arrives containing two state troopers arrives having been called for the stolen crop duster plane. Knowing that his could be his only chance for escape, the Hitcher yells at them that Maggie is trying to kill him. The police yet again believe him and they free the Hitcher and shoot Maggie in her left leg as she attempts to enter the truck's cab. Predictably, as soon as he is free, the Hitcher grabs a gun from the holster of one of the two policemen who free him, and in seconds, shoots and kills both cops. Maggie picks up a shotgun that she manages to retrieve from the truck's cab, aiming it at the Hitcher while limping away. The Hitcher taunts Maggie one last time by pointing his gun at her and saying in his typical sinister tone: "Are you still scared?" Maggie casually replies: "No. I just don't want to get burned." Maggie aims the shotgun at the tanker, which is leaking flammable fluid caused from the crash. Maggie fires a shotgun blast at the leak, igniting the fluid. The truck explodes, incinerating the Hitcher and blowing him to pieces. The film ends with Maggie dropping the shotgun to the ground and standing in the road facing the remains of the burning truck.