Zakes (William Ash) and his girlfriend Beth (Christine Bottomley) are driving along the rain-drenched M1 motorway at night, stopping at every service station so he can put up posters in the restrooms as part of his job. Tired and irritable, the two bicker continuously about their fragile relationship along the way. Beth is eager to tell Zakes she has recently cheated on him but can't find the right moment.
Beth soon falls asleep in the passenger seat. Moments later, failing to spot their exit, Zakes carelessly cuts up a large white truck, skids in the road and barely avoids a collision. The truck then violently overtakes Zakes before they come to a stop in traffic. As it does, the tailgate of the truck flips up, revealing a naked woman bound and bloodied in a cage, screaming for help. Before there is time for Zakes to get a cloeser look, the door is slammed shut.
Panicked, he wakes Beth up, telling her what he saw. They immediately call the police but are unable to tell them the number plate as it is covered in dirt. They describe the truck and where they are, and the police say they will take care of it. While stuck in the queue of traffic, Zakes gets out of his car and goes up to the truck. He manages to slide his hand underneath and take a photograph using Beth's phone, but it appears to be nothing but a white blur from the flash. As the traffic starts moving, the truck drives away and Zakes refuses to follow it as he has one last stop to make. Beth is furious and another argument arises, as she claims that he takes no responsibility and isn't bothered about anything other than himself and his job that he hates.
At the last service station stop, Beth tearfully ends the relationship and walks away. She calls her friend to come and collect her. Believing she will change her mind, Zakes decides to wait in the car for her. He then sees the truck from before pull up and watches a man in a dark, hooded jacket get out and go inside. Zakes follows minutes later to try and find Beth, but she is nowhere to be seen. While checking inside the women's restroom, he is thrown out by two security guards. He tries to explain that he is only looking for his missing girlfriend but they don't believe him. Zakes then finds Beth's necklace in the staff car park round the back of the station and believes she has been taken by the man in the truck, which has now left. Deciding to follow it, he returns to his car to find his tyre has been punctured by a group of rowdy football fans. Zakes steals a car from the station and starts driving.
Meanwhile, one of the security guards decides to look through the CCTV footage from that night to see if Zakes was telling the truth. He finds footage of Beth entering the station by herself and sees that she leaves through the back door with a man in a hooded jacket. Suddenly, he is killed by the other security guard, who is shown to be connected with the kidnapping as he calls the driver of the truck and warns him that Zakes is probably following.
At the truck stop, Zakes flees from the car and enters the site on foot. It is full of white trucks that all look identical. A police car then arrives and the officer arrests Zakes, believing he is trespassing. Handcuffed in the back of the car, Zakes explains what he is believes has happened to Beth and begs the police officer to check all of the trucks before they go. When the officer does, he is attacked and killed by the hooded man, which Zakes witnesses. He manages to escape from the car and runs into the woods nearby, followed by the man. He arrives back at the service station but Zakes knows he can't call the police for help as they believe he is a criminal, so he steals another car and drives it back to the site, adamant Beth has been taken there.
He parks up nearby to catch his breath. Suddenly, a bloody woman comes to the window, claiming she has been kidnapped and is in need of help. Zakes lets her into the car but tells her he needs to find his girlfriend. His phone battery then dies. Zakes remembers he saw a farm house not too far away, so he decides to drive there in order to call for help, now he has a witness who can back up his story. The elderly couple living there cautiously invite them in, and offer them a cup of tea and the chance to clean themselves up while they wait for help. The woman Zakes picked up offers to call the police but cuts the phone line beforehand, revealing that she too is part of the plan. She then calls the hooded man, telling him she will take care of Zakes.
The woman cuts the power in the house, kills the elderly couple and then attacks Zakes. He wakes up with his hands nailed to the floorboards, and realises the woman isn't who she said she was. He manages to get free just as she is ready to kill him, stabbing her in the eye with one of the nails. Bleeding and exhausted, he then takes her mobile phone and heads back to the truck site.
Outside, he finds Beth chained up in a cage. Frantic, she tells Zakes the keys are with the man, who is showering in a nearby shedhouse. Zakes quietly goes inside and finds several other women locked up and gagged, who beg for his help. He manages to get the set of keys from the man's clothes on the bathroom floor and returns to Beth to help her escape first, promising he will be back to help the others. It appears the women are being used for human trafficking. While trying to find the right key, they hear the man coming and Zakes has to flee. A cat-and-mouse game soon begins when the man realises he is hiding in the site somewhere. He calls the woman's phone, which Zakes has on him, and follows the ring to where he is. However, Zakes has left the phone on the seat on an empty truck and is hiding in the forklift nearby. When the man steps into the right spot, Zakes pushes a button in the vehicle, and the crane releases a heavy load onto the attacker, crushing him instantly.
Zakes then runs back to help Beth who has already freed herself using the screwdriver he gave her. The pair reunite, sobbing with relief.William Ash as Zakes Abbot
Christine Bottomley as Beth
Andreas Wisniewski as The Tarman
Claire Keelan as Wendy
Stuart McQuarrie as Thorpe
Robbie Gee as Chimponda
Peter Wyatt as Mr. Coates
Sheila Reid as Mrs. Coates
Shaun Dingwall as PC Mitchall