Corky Withers is a struggling magician whose career transforms after he adopts a foul-mouthed ventriloquist dummy named Fats. The duo's act gains instant popularity, propelling Corky into the limelight. However, when his agent Ben Greene suggests a medical evaluation due to Corky's eccentric behavior, Corky opts to retreat to a secluded mountain cabin. There, he reunites with his high school crush, Peggy Ann Snow, who is now trapped in an unhappy marriage. As Corky and Peggy rekindle their old feelings, they plan to escape their troubling pasts and begin anew. Corky’s connection with Fats, however, grows unnervingly intense, blurring the lines between his own identity and that of the dummy.

Peggy’s strained relationship with her husband Duke and Corky's unpredictable attachment to Fats culminates in rising tensions. Duke eventually grows suspicious of Corky's intentions, leading to an escalating confrontation. This clash sets the stage for an exploration of Corky’s deteriorating mental state and the sinister control Fats appears to have over him. The film’s narrative stays tightly woven around themes of obsession, fear, and psychological disintegration. The boundary between reality and illusion becomes increasingly difficult to discern as the stakes climb higher, leaving viewers questioning the very nature of Corky's tenuous grasp on his own psyche.