Andrew McGee and his nine-year-old daughter, Charlie, are on the run from the Department of Scientific Intelligence (DSI), a clandestine government agency known by the nickname, “The Shop.” During brief breaks in their journey, Andrew recalls the events that changed their lives. To earn extra money during college, Andrew participated in experiments involving a hallucinogenic drug called “Lot Six,” which was secretly sponsored by the Shop. There, he met fellow student and volunteer, Vicky Tomlinson, and the two later married. As a consequence of the experiment, Andrew and Vicky are left with certain psychic abilities: she can read minds and Andrew is able to force others to perform his will through mind control. However, their daughter Charlie is born with a greater destructive potential, the ability to start fires telepathically. She also possesses foresight into the immediate future. As Charlie grows up, her father coaches her on controlling the power, and at breakfast one day, instructs her to toast the bread, and not set it on fire. However, Charlie has difficulty restraining her pyrokinesis, if overwhelmed by anger or frustration. Meanwhile, the McGees receive anonymous telephone calls and suspect the Shop is monitoring them. One day, Andrew arrives home to find that two Shop agents have murdered Vicky, but he is able to prevent them from abducting Charlie by using mind control. Father and daughter escape and become fugitives over the next year. At a plantation in Longmont, Virginia, which serves as Shop headquarters, Dr. Joseph Wanless, the doctor in charge of the “Lot Six” experiment, alerts the head of the organization, Captain Hollister, that Charlie’s ability could increase in adolescence as her pituitary gland develops. Wanless compares the possibilities to a nuclear explosion. Hollister looks at John Rainbird, the organization’s deranged assassin, and ponders the option of using the girl as a military weapon, but Wanless is adamantly against the suggestion. On their way to Tennessee, Andrew and Charlie hitch a ride with Irv Manders, who invites them to his farm for lunch. Irv is immediately charmed by the adorable Charlie and mentions he and his wife Norma always wanted a girl. Andrew senses he can trust the older man and confides about their abilities, the Shop, and the fact that the agency wants to use Charlie to reactivate the Lot Six project. After Charlie suddenly foresees agents converging on the farm, Irv agrees to protect the two fugitives and grabs his rifle. When Shop agents seize her father, Charlie sets the men on fire and causes their cars to explode. Irv gives his friends an old Jeep, and father and daughter drive to a mountain cabin where Andrew’s father once lived. Hoping to force the Shop to back down, Andrew writes letters about their situation to major newspapers, such as the New York Times, and mails them from a local post office. Meanwhile, back at Shop headquarters, Rainbird assassinates Dr. Wanless, and Hollister receives information on the McGees’s location from two undercover agents in the mountain area. Hollister sends Rainbird to apprehend the father and daughter, but the assassin also wants to dispose of the girl once the Shop has completed their tests. He believes she possesses “the power of the Gods” and must be eliminated. After confiscating the mail delivery containing Andrew’s letters, Rainbird hides in a tree and captures the McGees using a tranquilizer gun. At Shop headquarters, father and daughter are separated in the plantation’s mansion, and Andrew is given medication to weaken his mind control powers. Charlie is combative and demands to see her father as Hollister attempts to seek her cooperation. The captain tries to cajole Charlie with toys, but she remains defiant and refuses to demonstrate her pyrokinesis, especially after the destruction she caused at the farm. Posing as an orderly named “John,” Rainbird cleans Charlie’s room every day and works on befriending the young girl. He eventually succeeds in convincing her to cooperate with the Shop’s tests, under the pretense that she will be allowed to see her father. In the control room, Hollister becomes ecstatic when Charlie sets fire to wood chips and makes a bathtub of water boil. Rainbird continues to foster a relationship with the girl and takes her horseback riding one day. Charlie tells the “orderly” that her power feels stronger and she is able to control it more. In the next experiment, she sets fire to a cinder-block wall, but threatens greater destruction when Hollister and his team will not let her see her father. Meanwhile, Andrew has been undergoing tests, but has learned to fake swallowing the pills and gives the impression that his mind-control abilities have weakened, so the Shop will lower its guard. When Hollister reveals the Shop is sending him to Hawaii for some rest and relaxation, Andrew knows the trip is a ruse and uses his mind control to make Hollister relay a note to Charlie. Andrew instructs his daughter that they will be leaving that night and to meet him at the stables at 8:00 p.m. Excited, Charlie shares the plan with her new friend “John.” On the way to the stables, Andrew learns from Hollister, who is still under his mind control, about Rainbird’s role in the scheme. Meanwhile, Rainbird goes to the stables and stakes out a spot in the barn loft. He persuades Charlie to climb the ladder and join him there, but she stops as soon as she sees her father and runs to embrace him. When Andrew informs his daughter that “John” is not a friend, she is furious about the deception and prepares to set fire to the barn. However, she pulls back her powers so as not to hurt the horses. In an effort to seize Charlie, Rainbird kills Hollister with a bullet to the head and wounds Andrew with one in the neck. He tries to shoots Charlie, but she sets the bullet on fire and turns it back on Rainbird, making him burst into flames. Dying, Andrew tells his daughter to flee, kill anyone that tries to stop her, and burn down the Shop. After her father passes away, Charlie lets the horses escape before destroying the plantation and targeting Shop agents with fireballs. Later, she returns to the Manders farm and is embraced by Irv and Norma. Accompanied by Irv, Charlie follows through with her father’s wishes and goes to the New York Times to tell her story.