The plot revolves around three angry teenagers in a small, blue-collar town.
Don Calhoun, the main character, is angry because he is a poor, pimply-faced teenage loner who yearns to be the most popular boy in school. Behind the pimply-faced exterior is a restless spirit seething with hate, and revenge - a deadly combination.
It's the 60s, and drugs, and the free-love movement have taken hold in California. Through an acquaintance who has just returned from San Francisco, Don gets his hands on devil worship literature and a small wooden statue that was used in Satanic worship ceremonies.
Don reads some of the literature, and concludes that selling his soul is the only way he can possibly realize his dream. But he really doesn't think it's possible.
Across town lives another angry, miserable teen. His name is Eddie, and all he wants is to become the greatest rock-'n'-roll guitar player in the world. Eddie and Don are members of the zit squad at high school; at least that's what the jocks, and cheerleaders call them.
Laura once was a cheerleader and hung out with the other cheerleaders, and jocks. But that was before she was paralyzed in a diving accident, and ended up a "wheelchair-bound freak." Now her obsession is to walk again, and regain her rightful place among the beautiful people., and like Don, and Eddie, she becomes bitter and vengeful.
Don is the first to take the plunge into the supernatural by conjuring up a demon that arranges for him to sell his soul to the big man himself. In just a matter of days, Don's new-found strength, and powers enable him to destroy some of his tormentors.
Only one person in town can sense the presence of evil, and the death, and destruction that will follow. But long ago she was labeled a religious nut, and nobody takes "poor old' Anna" seriously.
Don discovers that the ancient man who owns all the mills in town already is in league with the devil, having sold his soul a century earlier. Don is encouraged to recruit three more devil worshipers so the coven will be a complete thirteen members.
Cruel events soon have Eddie, and Laura eager to take the plunge after Don, and he easily convinces them that their souls are small prices to pay for the good life.
To make their deal, Don, Eddie, and Laura must sacrifice a human to Satan. Don chooses one of his teachers who delights in humiliating him in class, Eddie chooses a fellow student who ridiculed his music, and Laura chooses the girl who once was her best friend, but became her worst enemy after the accident. Each sacrifice is carried out in a bizarre, sadistic manner.
The bodies soon begin to accumulate. Police launch an investigation but have few leads and very little incriminating evidence.
Phillip Sawyer, a newspaper reporter fresh out of college, begins his own investigation hoping to find fame, and fortune after breaking the case.
And Anna keeps having visions of the murders and senses the growing evil. She tries to warn people, and get someone to help her, but of course, nobody believes her foolish story.
In the end, Anna realizes she must battle Satan by herself, and sets out to prove she is the chosen one. Her tattered Bible guides her. In one test she handles a rattlesnake and drinks poison. She then raises a dog from the dead. But the ultimate test comes when she has to discard all her worldly possessions.
The young reporter trails Don, Eddie, and Laura to the old barn where they have set up an altar to worship Satan. Sawyer is caught spying on them and is asked what his last wish is before they cut his throat, and feed him to the rats. To buy time, Sawyer tells them he wants to interview the devil. He is tied up and tossed into the cellar of the old barn.
A few days later, Don arranges the interview at the mansion of the mill owner. During the interview, Sawyer makes a fatal error, he mentions Jesus Christ which infuriates Satan. Sawyer is retied and dumped back into the cellar.
