Oklahoma, 1978: Tammy and her friends break into the abandoned Darkland Amusement Park, long associated with the cult founded by Dexter Venito. By morning most of the teens are dead and Tammy is mysteriously missing. This draws the attention of private investigator and former cop, Atticus Fairbanks.

1940's California: Failed actor Dexter Venito works as a janitor at a carnival freakshow ruled by the sadistic vampire Vladislav. The lone bright spot in his life is a budding romance with the show's star attraction, a "mermaid" named Lisette. Inspired to flee for a better life, the pair are thwarted by the jealous Vladislav. Dexter is beaten and left to die in the desert.

Detective Fairbanks and Elsa are reeling from the discovery of Theodosia Birchwood, alive and completely unaged after having been missing for 25 years. Desperate to break through to the catatonic Theodosia, Fairbanks is convinced there's a connection between her and the Tammy Gillis case-the ring Theodosia stole from Dexter decades previous.

1950's Oklahoma: FBI Agents Reed and Milner are tasked with infiltrating a cult run by Dexter Venito, the Dex Venetians. As Milner buys into his new lifestyle, Reed grows closer with Theodosia, who runs the cult's animation studio. Reed becomes increasingly alarmed at the Dex Venetian's aims.

1978 Oklahoma: Following a clue from Theodosia, Fairbanks and Elsa confront Braxton Chamberland, the architect of the Darkland Amusement Park. Braxton shines a light on the cult's rise, Dexter's abusive behavior toward Theodosia and the building of a roller coaster, a machine of great importance to the prophecy of the Erendu.

1940's Florida: Theodosia Birchwood lives under the thumb of her stern and abusive mother, Miriam. Her only friend is her younger sister, the talented golden child, Lavinia. When her father, Mordechai, returns from his treasure hunting expedition with a cursed sarcophagus Theodosia becomes obsessed with the artifact.

Oklahoma, 1978: After passing through many hands, the ring Theodosia stole back from Dexter in the '50s makes its way into Tammy Gillis's possession. Obsessed with Dexter Venito and his cult, Tammy convinces her friends to break into the long abandoned Darkland Park. As they party, Tammy dares them to perform a ritual in Dexter's honor.

Following his escape, Ollie returns to the Darkland Amusement Park to awaken Dexter from a cryogenic chamber. And now within Dexter's grasp are all the elements needed to open a portal to the Erendu. When Fairbanks, Elsa and Theodosia infiltrate the park and confront Dexter, a battle for control of the ring ensues.