Terravex Oil is in the midst of a fracking operation near a lake in North Dakota, overseen by CEO Reece Tenneson and geologist Jim Dowd. The operation releases three subterranean creatures and destroys the drilling rig. Two are captured by Terravex, but one of them escapes the site. Meanwhile, high school senior Tripp Coley is looking for something to do to escape the life of his family; his parents are divorced, his mother Cindy is in a relationship with Rick the town’s sheriff, who fails to take him seriously, and has taken up a part-time job at a local junkyard, where he builds a pickup truck in hopes of being able to leave his town. One night, Tripp encounters the escaped creature in the junkyard and captures it, but the creature escapes before he can seek authorities.
The next day Tripp, along with classmate Meredith, finds the creature has a diet of oil and it takes shelter within the hood of his truck. He quickly befriends him, names him Creech, and promises to help him get home. Tripp modifies the truck to give Creech more control over the truck as a makeshift engine, and Meredith becomes quite impressed and surprised at Creech’s speed and talent. Meanwhile, Tenneson is still concerned about the incident at the drilling rig that exposed Creech, since similar experiments have revealed the other two creatures. He decides to protect the company’s image by drilling poison into a hole leading to the underwater tunnels, and by sending hired mercenary Burke to kill their captured creatures, to the objection of Jim, as he finds the monsters have significant intelligence and emotions. Tripp and Meredith go see Tripp’s dad Wade to seek help.
When Tripp goes to check on Wade, however, he realizes he sold him out to Burke, and Tripp and Meredith escape in the truck with Creech, but not before destroying Wade’s trailer. Tripp, Meredith, and Creech are chased by Burke and his team and Rick. Tripp, Meredith, and Creech manage to escape by jumping over a train, and camp at a hunting cabin owned by Meredith’s father near the lake, while Rick chastises Burke for attempting to follow them himself.
When Creech gets the sense something bad will happen to the other creatures, he heads to the Terravex headquarters where the other creatures are being held captive. Tripp and Meredith follow Creech using Meredith’s cellphone, as Trip left his phone in the truck. When they arrive, they find Creech’s parents, but are attacked by Terravex workers. Creech arrives and is captured; Tripp and Meredith are taken to Tenneson, and he tells them to forget about Creech and his parents and has Burke escort them out.
Sympathetic to the creatures’ plight, Jim decides to help Tripp and Meredith rescue the creatures. With the help of Tripp’s junkyard boss, Mr. Weathers, they acquire two more trucks, one being a repossession from a rich teen who had failed to make payments, and another being the birthday present of his friend Sam Geldon, whose father owns a local car dealership. They modify the trucks for Creech’s parents to control similar to Creech in Tripp’s truck. Jim helps the group by stealing the Terravex truck on which the monsters, Creech’s parents, are loaded on. At the dealership, the creatures take control of the modified trucks and the group make their escape up the mountain leading to the tunnels.
Terravex gives chase up the mountain and the group escape by using the trucks to jump over the edge of the mountain. On the way, Rick helps Tripp and the group escape from Burke. After realizing the poison has been inserted, Tripp gets into a head-on battle with Burke, who attempts to push him into the drilling hole, and Tripp overturns Burke’s truck, destroying the poison machine, but not without falling into the hole. Creech saves him from drowning before he and his parents depart back home and Terravex is exposed by the group for the experimentation that was harming the creature’s habitat. Tenneson is arrested, Tripp and Rick develop on good terms and together build a new engine for the truck, and Tripp and Meredith begin a relationship.