Teenagers Charlie Sykes and Rachel Clark elope to Las Vegas, Nevada, accompanied by their dog, “Mr. Ben.” Concerned their parents have alerted police, they turn off the main highway onto a back road. Charlie stops the car and wants to make love, but Rachel refuses, insisting their first sexual encounter should be in a bedroom. When they stop at Sam’s Last Chance gas station, Sam cautions them to return to the main road, but Charlie and Rachel are eager to reach Las Vegas. Sam tells of two Joshua trees by the road, and warns them not to fall asleep until they pass the second one. Rachel is soon asleep and, as they pass the first Joshua tree, Charlie falls asleep at the wheel, but awakens in time to avoid crashing into a billboard near the second Joshua tree. As Charlie stops, he notices a police car behind the billboard, and Sergeant Bedlam, also known as “Hellcop,” strides to their vehicle, rips open the passenger door, and pulls Rachel out. Charlie fights the officer, but is knocked out. When he regains consciousness, Rachel and Hellcop are gone. Charlie returns to Sam’s gas station, and learns of the hidden “highway to hell,” where many virginal young women have disappeared. Fifty years earlier, Sam and his fiancée, Clara, fell asleep while driving between the Joshua trees. Clara disappeared, but Sam has never given up hope of finding her. He insists Charlie must stop Hellcop from taking Rachel to Hell City. To find the highway to hell, Charlie must drive between the Joshua trees and truly believe it exists. Sam arms Charlie with a “special” rifle and several shells. Realizing Charlie’s vehicle is inadequate, Sam offers his classic car. Charlie races between the two trees until a police car stops him. Certain it is Hellcop, Charlie aims his rifle at Jimmy, the young officer. Realizing his error, Charlie speeds away while chanting, “I believe.” His car is transported through a portal to the hell highway in a remote desert. Meanwhile, Hellcop drags Rachel into Pluto’s Donuts, a hellish diner filled with police officers in various states of deterioration. Hellcop shoots an annoying officer, who disappears in an energy surge. While Hellcop’s attention is diverted, Rachel runs away into the desert, where she is surrounded by a motorcycle gang, led by Royce and his girl friend, Clara. Royce returns Rachel to Hellcop, in exchange for a future favor. Later, Charlie meets the motorcycle gang at the diner and recognizes Clara. Royce allows Charlie to go free after elicting a promise that Charlie owes him a favor. When Charlie reaches Hellcop’s car, the two exchange gunfire. Charlie is forced off the road and crashes in the desert as Hellcop speeds away. A tow truck arrives, and the driver, Beezle, is accompanied by Adam, a child who is excited to meet Charlie’s dog, Mr. Ben. Beezle fixes Charlie’s car and advises him that all roads lead to Hell City. Later, Charlie is surprised to discover Adam hiding in the car, and wonders how the boy got into hell. Adam fell asleep during a family trip and awoke to find Hellcop had murdered his family and dog. Hellcop brought him to Beezle, who is teaching Adam how to “fix things.” Charlie promises Adam that he and Rachel will take him out of hell. Charlie parks at a casino by Hellcop’s car. While Adam stays outside, Charlie enters the crowded club. He sees Rachel locked in a cage, and shoots at Hellcop, to no effect. In return, Hellcop shoots Charlie in the chest and leaves with Rachel. Adam rushes to help Charlie, who is bleeding badly. Beezle arrives and promises to save Charlie if Adam pledges to stay in hell. Charlie awakens, surprised to be healed, and Beezle acknowledges that Hellcop’s bullet could not pierce his soul. Beezle suggests that Charlie take a shortcut called the road to nowhere, and Royce’s gang arrives as Charlie leaves. Charlie asks Adam to join him, but the boy tells him he must stay with Beezle. A jealous Royce confronts Beezle about favoring Adam, and Beezle berates Royce. Angry, Royce leads his gang to hunt Charlie. However, they do not follow when Charlie speeds onto the Road to Nowhere. Charlie sees Hellcop’s car parked outside a cave. Clara races up on her motorcycle, and Charlie reveals Sam is still looking for her. She warns him not to take the shortcut because he may have to make a difficult choice there. She admits Satan tempted her, and she made the wrong choice. Charlie insists on finding Rachel, and enters the cave. He climbs a flight of stairs and finds Rachel tied up inside a bedroom. She demands they make love, but Charlie hesitates. Hellcop bursts inside and they fight. Charlie grabs Hellcop’s gun and shoots, causing the officer to disappear. Rachel again demands they make love, but Charlie looks in a mirror and sees the reflection of a demon instead. Charlie shoots the demon, and it falls through the bed into a hellish pit. As Charlie returns to his car, Hellcop’s car surges with energy and transports itself onto the crowded highway to Hell City. Charlie follows into a mountain tunnel, but takes a wrong turn to the edge of a cliff across the chasm from Hell City. He hikes down the mountainside and joins travelers boarding a boat on the River Styx. The ferryman claims only the dead can pass, but acknowledges rules can be broken and warns Charlie it is a one way trip. Inside Hell City, Charlie eludes guards and discovers Rachel playing violin in a luxurious room. The monstrous-looking devil enters, and Charlie demands to leave with Rachel. However, Satan claims he has heard Rachel play violin and knows she can be successful with the devil’s help. Rachel refuses the offer, insisting she loves Charlie. Satan allows them to leave on condition that they do not look back. As they leave, Satan transforms himself into Beezle. Guards chase Rachel and Charlie to Hellcop’s car. Rachel hotwires it, and they speed out of Hell City, across the canyon and into the mountain tunnel. Charlie shoots Hellcop’s engine, and then retrieves his car. Mechanics fix Hellcop’s car and he pursues the couple. Rachel and Charlie stop at a large mansion and discover Beezle and Adam waiting. Charlie wants to take Adam with them, but the boy refuses to break his promise to remain. Charlie counters that he must fulfill his promise to the boy. Adam is surprised that Charlie is honoring his word, and runs to him. Beezle admits he is the devil, and refuses to let his “adopted son” go. Charlie offers to race Hellcop in exchange for Adam, but Beezle refuses. However, Rachel offers herself as part of the prize, and Beezle accepts. Hellcop and Royce’s gang arrive. Charlie, Rachel, Adam, and Mr. Ben get into their car, and Clara asks them to say hello to Sam for her. As the race begins, Beezle declares Royce is a great disappointment, and Royce’s gang deserts him. Angry, Royce jumps on his motorcycle with Clara, and chases the racers. He reaches Charlie’s vehicle and tries to stab Adam with a sword. However, Clara insists he let them live, places her scarf over Royce’s face, and they crash in the desert. Meanwhile, Adam reveals the only way to kill Hellcop is to shoot his sunglasses. They have one shell left, but it drops to the car floor. As Rachel reaches for it, she sees a box hidden under the seat. She flips the switch, and they accelerate through the portal to Earth, crashing by the billboard on the back road. Jimmy, the police officer, is shocked by their arrival, and pulls Charlie from the car. As he handcuffs Charlie to the police cruiser, Hellcop bursts through the billboard. Jimmy fires at Hellcop and is knocked aside. Hellcop attacks Charlie, who grabs a hubcap and shatters one of Hellcop’s lenses. As Hellcop aims his weapon at Charlie, Rachel loads the last bullet into the rifle and shoots Hellcop’s face. Light streams from his eyes and Hellcop explodes. Later, Charlie and Rachel get married with their parents’ blessing. Their journey through hell inspires Charlie to develop the phenomenally popular video games, “Hell on Wheels,” “Dog in Hell,” and “I’d Rather Be Living.” Rachel opens a chain of Hot as Hell Pizzerias and sometimes serenades the customers on her violin. The two of them are very happy, but they have vowed never to take back roads at night again. Adam now lives with his aunt and uncle in Cleveland. He has his own dog, but still sends a postcard to Mr. Ben every Tuesday. Sam still stays up late warning people about the highway to hell. He has not given up hope of seeing Clara again. Mr. Ben now stars in his own dog food commercial. For Beezle, the game goes on.