For several hundred years, a secret sect known as the “Druids” have protected the Earth from the return of Satan’s son using six magical runestones. One night, the Druids attempt to save a mortal woman who has been chosen as a surrogate, but the ritual is interrupted when Christian crusaders, who view the Druids as Devil worshippers, steal four of the stones. In present day California, a Druid named Will Travis discreetly uses his powers to protect his teenage son, Kenny, from the class bully. Later, lightning strikes the ground, and Will senses something evil is approaching. Meanwhile, a New York City woman prepares for a date and decides to wear a pendant containing one of the magic runestones, which has been passed down as a family heirloom. As the moon and sun align in a lunar eclipse, the woman convulses violently and a child rapidly grows inside her womb. A gurgling mass bursts from her body and morphs into the form of an adult man, who follows his bleeding “mother” through the apartment, demanding a kiss. Once she is dead, Satan possesses her body and instructs his son, the “warlock,” to free him from the prisons of hell by collecting the five remaining runestones before a solar eclipse occurs at the end of the week. Using a piece of the woman’s flesh to make a map, the warlock steals her boyfriend’s clothes and coerces a taxicab driver to take him to Chicago, Illinois. Back in California, Kenny argues with his girlfriend, Samantha Ellison, about his desire to attend college in Berkeley, and escape his reputation as the son of a rumored Satanist. Suddenly, Kenny’s father appears with his fellow Druid, Franks, and kills Kenny with a shotgun. In the Druids’ dungeon, Will uses magic to revive his son as a Druid warrior, and explains the warlock’s plan to annihilate the Earth. Will and Franks ask Samantha’s father for help, but Ted Ellison has since denied his affiliation with the Druids to serve as a minister of the Gospel to the town. In Chicago, the warlock interrupts a fashion show to retrieve a stone dangling on the earring of one of the models. When designer Paula Dare refuses to relinquish the relic, she accompanies the warlock to the roof, and he levitates her several yards above the building. Terrified, she gives him the stone, but the warlock releases his grasp and sends her crashing through a glass skylight below. As the warlock continues west, Franks discovers a spell that causes the evil wizard to spew black blood. Although momentarily weakened, the warlock regains his strength by attacking a gas station attendant and resumes his journey in a stolen sports car. He obtains a third stone from a traveling circus, and traces the fourth to the office of a wealthy collector. Over the next few days, Will trains Kenny to use his powers. As Samantha struggles to process the meaning of Kenny’s new role, Will reveals that she is also destined to be a warrior. She confronts her father for keeping her identity a secret, and plunges a knife into her stomach so that Will and Franks can revive her with magic. Once she is “reborn,” Samantha and Kenny make love and prepare for battle. Kenny reveals he owns one of the salvaged stones, and entrusts it to Samantha. With four stones in his possession, the warlock drives to California and issues a warning to the Druids by crucifying a woman on an inverted cross. In the morning, he tortures Franks into surrendering the fifth stone. Kenny and the warlock battle, but Kenny is impaled on a metal pole. Demanding to know the location of the final stone, the warlock injures Will and Ted Ellison. Just then, Samantha appears on a motorcycle and invites the warlock to chase her. Despite her attempts to stave him off, he follows her into the forest, ties her to the grille of a truck, and steals the stone from around her neck. As the moon eclipses the sun and pitches the forest into darkness, the warlock begins the ritual to summon the Devil. Miraculously healed with a Druid potion, Kenny arrives and attempts to stop the warlock, but is bound to a tree by his foe. The runes open a portal in the ground, allowing Satan to emerge. Kenny and Samantha use their powers to turn on the truck headlights, which stunts the ceremony. As daylight returns, the vengeful warlock attempts to stab Kenny with an ancient dagger. The two young Druids telekinetically deflect the blade into the warlock’s chest, causing him to dissolve into a pool of black blood. Samantha collects the runestones, but the warlock’s skeletal hand briefly emerges from the ground and pulls one of them from her grasp. With five stones remaining, Kenny and Samantha emerge limping from the forest.