Electronics repairman Bobby Grady (John Laughlin) finds himself in a rather convoluted situation when he attends a group therapy session at the behest of his friend Donny Hopper (Bruce Davison). Initially, Bobby appears confident, proudly sharing that he has been happily married for 11 years to his high school sweetheart, Amy (played by Annie Potts), and together they have two young children. However, the dynamic of the group weighs on him when someone suggests that he is inadequate as a lover, leading to his revelation about frustrations stemming from their infrequent intimacy.
As the night unfolds, Bobby comes home late to face his wife’s complaints about their financial struggles. To alleviate the burden, he reluctantly accepts a side gig performing nighttime surveillance for Lou Bateman (Norman Burton), who suspects that Joanna Crane (Kathleen Turner), a talented designer at his sportswear company, is stealing proprietary patterns and selling them to rivals. Bateman's unfounded mistrust of Joanna, a driven and enigmatic woman, sets the stage for Bobby's next series of discoveries.
While clandestinely trailing Joanna, Bobby is astounded to discover her alter ego: she transforms into a sultry, seductive figure named China Blue, moonlighting as a prostitute at the Paradise Hotel in downtown Los Angeles. Bobby’s shocking revelation comes to fruition as he captures footage of her engaging with Peter Shayne (Anthony Perkins), a deranged street preacher who becomes a frequent patron of the mysterious China Blue. Shayne, a figure both unsettling yet compelling, does not seek physical relations with her; he instead pays her to talk, all the while battling his mental demons and an obsession with her brazen persona.
During one particularly tense encounter, after a brief but intimate liaison with China Blue, Bobby realizes that she may be more than just a fantasy. His heart races as he grapples with the connection between them—a feeling that joys in the depths of longing and the thrill of the unknown. However, the strange threads intertwining Bobby's life with joy and danger become increasingly tangled when Shayne, exhibiting erratic and violent tendencies, begins to stalk Joanna, revealing dark truths that bind them all.
After a string of confrontations and emotional upheaval within his marriage, Bobby finds himself seeking the solace of Joanna, whose own insecurities mirror Bobby's struggles. Their connection crescendos, but the jagged knife of reality continues to pierce through the romantic veil. Shayne's obsessive nature escalates to a boiling point when he breaks into Joanna’s apartment, wielding a large vibrator that he menacingly refers to as "superman," attempting to exact a grim cure for their shared dysfunction.
In a twist of fate, Bobby arrives at a crucial moment, unwittingly confronting Shayne as Joanna emerges from the shadows, ultimately standing her ground. In a chaotic turn of events, she fatally stabs Shayne, a climax reflecting the ultimate struggle of saving oneself from the chains of the past.
After this harrowing experience, Bobby returns to the group therapy session, a profound shift in his demeanor noted as he declares his permanent separation from Amy. Battling his inner demons and looking toward a hopeful future, Bobby expresses his newfound happiness in his relationship with Joanna, who stands as a beacon of change, symbolizing redemption and the courage to face one’s fears. In this intricate tapestry of life, relationships, and self-discovery, each character weaves in and out, leaving behind a trail of emotional testament to the complexities of human desire.
