彭妮在童年时期经历了一场车祸，她的父母在这场车祸中双双身亡，彭妮虽然侥幸逃生，却因此留下了严重的精神创伤。经过多年的各种治疗，彭妮的精神医生决定带彭妮重返当年的事故现场，希望通过这种治疗方法帮助彭妮鼓起勇气重新去面对当年的惨剧，克服她对汽车的恐惧。两个女人一路驾车前行，不知不觉开到了一条寂静的山间高速公路上，发现路边有一位搭便车的神秘男子。出于好心，她们让这个男人上了车，但没有想到的是，这个神秘男子是个极其残忍的嗜血杀手，当他上车时，她们的治疗之旅转变为了死亡之旅，彭妮碰到了比她多年的梦魇更为可怕的事情……
Penny, (Rachel Miner), a young woman traumatized by a childhood auto accident that killed her parents, accompanies her therapist Orianna (Mimi Rogers) on a road trip to a mountain community as part of her therapy to overcome her fear of cars. On their way up a secluded road Orianna finds out that Penny is taking sleeping pills. This greatly disappoints Orianna as the pills only slow Penny's recovery.
She explains this to Penny in frustration and fails to notice a hooded hitchhiker standing on the side of the road. Orianna accidentally hits the hitchhiker and then offers the hitchhiker a ride to their destination, which happens to be an even more secluded location. The Hitchhiker remains completely silent during the drive with his hood pulled up to conceal his face. The only action the hitchhiker takes, besides silently offering them a skewer of raw meat, is checking out the bag in the backseat containing a book written by Orianna which then leads to Penny explaining the reason for their trip and her severe fear of cars.
Orianna and Penny drop off the hitchhiker in the middle of the road going through a camp which is closed for the season. The duo does not get too far, however, due to a flat tire caused by the Hitchhiker, who punctures the tire with one of the meat skewers. Orianna insists that Penny wait in the car while she goes to try to get reception on her phone and call for help-much to Penny's disapproval as she knows the hitchhiker is waiting out there for them.
Orianna sets out for help but she doesn't get far when she sees a bright light in front of her. Penny waits anxiously in the car; after half an hour she realizes something has gone wrong. She leaves the car and tries to locate Orianna. Penny finds a phone and tries to call for help, but the phone is disconnected. As she turns around she sees the hitchhiker behind her, and tries to run but falls and hits her head.
When Penny wakes up, she is sitting in the car again, with the video camera in her hands. She turns it on to find a video recently recorded. She watches the video in horror as she realizes that the hitchhiker taped the murder of Orianna. Penny starts to panic, and when she looks to her side she sees Orianna's dead body in the seat next to her and realizes that she is trapped in the car between two tall, thick trees and there is no escape.
Penny tries to call for help, but the hitchhiker continues to terrorize and torture her. A man who works in the mountains tries to help, but is killed by the hitchhiker who is hiding under the car. The man's mistress is also killed nearby, while waiting for a tryst in the woods. The man's bearded co-worker comes looking for him, but falls down a hill and is killed by the hitchhiker as well.
Penny is tortured for another few hours and when she tries to crawl out of the car window, the hitchhiker grabs her right foot and cuts off one of her toes. Penny continues to take sleeping pills and painkillers to escape the madness. When she awakes for the last time, she turns around to find the hitchhiker (a wild-eyed scruffy woman) sitting in the back wearing Orianna's clothes, who then tries to strangle her while saying, "Don't forget your breathing exercises, Penny". She manages to fight off the hitchhiker and escape from the car, only to trip from her injured foot. The hitchhiker finds her and tries to attack but a man driving a pick up truck drives past in time to hit the hitchhiker with his truck. The hitchhiker appears to be dead at this point and the truck driver is panicking. He tells Penny to wait in the car while he assists the hitchhiker. Penny feels a bit of relief as she watches the man and the dead hitchhiker. But terror boils up when she realizes the hitchhiker is still moving...
