Wealthy psychiatrist Dr. George Parson Danny Rogers is bludgeoned and drowned in his pool, an event Christie Parson Mary Elizabeth McDonough believes was murder, while Eve Parson Lynda Day George insists it was an accident. The family’s coastal estate becomes a quiet stage for doubt and fear as Christie starts to sense that dark forces may be at work around her father’s death.
Weeks later, Josh Denis Mandel, an ex-employee at a local mortuary, sneaks into the mortuary warehouse with Christie’s boyfriend Greg David Wallace, intending to steal tires to cover unpaid wages. Inside, they witness an occult sabbath that Josh has become inured to after previously seeing something similar. While they gather tires, a cloaked assailant strikes, and Josh is stabbed to death with a trocar. Greg, shaken, sees a van speeding away and assumes Josh was driving it, deepening the sense that someone is orchestrating danger behind the scenes.
That night, Greg and Christie search for Josh at the nearby roller skating rink but come up empty. The next day, Christie is pursued by a car as she and her family retreat to their secluded coastal mansion. After a heated argument with her mother, Christie—who has begun sleepwalking in the wake of her father’s death—awakens by the pool to find herself confronted by a hooded figure. She escapes, and Eve reassures her that it was only a nightmare. The following day, Greg confesses that he saw Eve at the sabbath, prompting Christie to suspect that her mother and Hank Andrews Christopher George, Hank’s son Paul’s father, may be involved in a plot to drive her insane or worse.
In parallel, Paul Bill Paxton, Hank’s son and an embalmer at the mortuary, pursues Christie with noticeable eccentricity. He—like the family—seems drawn into the eerie atmosphere surrounding the death and the rituals at the mortuary. Christie and Greg begin to see that the family’s tensions extend beyond jealousy or rumor, tying the supernatural with a very real, dangerous plan. Their suspicions grow as a séance at the mortuary is revealed to involve Eve and Hank and the women from the earlier meeting Josh and Greg had witnessed; they try to contact Eve’s late husband, and Christie realizes Eve and Hank were not dating as she had believed. The table moves, and Hank speaks to Christie’s father in an attempt to reach him, saying that George’s death was not an accident and that someone else caused it. The connection is broken, and Christie and Greg leave, unsettled by what they have learned.
That night, Christie is attacked again by a cloaked figure who resembles Paul, and she smashes a window in a panic that Eve attributes to a nightmare. Eve then wonders aloud whether the attacker could have been Paul, explaining that Paul had been a patient of Christie’s father and had developed an unhealthy fixation on Christie, though they had dismissed him as dangerous. Soon after, Christie and Eve return to their rooms, only to be confronted by a brutal revelation: Paul kills Eve with a stab while she lies in bed, after which Paul—now wearing a white latex mask—chases Christie through the house.
Paul drags Christie to the mortuary and begins an embalming process that aims to keep her alive for his warped purposes. He justifies his actions as punishment for Eve telling Christie about his psychiatric condition and reveals that he murdered Dr. Parson once in a rage after the elder man suggested treatment. He then stabs his father Hank in a fit of anger, before being confronted by Greg, who has managed to break free and arm himself with an axe. Greg’s arrival shifts the balance of power, and he and Christie defend themselves in the warehouse.
Paul has arranged a makeshift wedding ceremony among the preserved bodies, including the body of his mother, Mrs. Andrews [Donna Garrett], whom he has kept in a coma and whose death he had faked. He performs his macabre ritual as if conducting a Mozart symphony, intending to claim Christie in a final, deadly ceremony. In the struggle, Christie’s sleepwalking takes on a new urgency as she seizes an axe and drives it into Paul’s back, ending his rampage. Greg and Christie share a relieved embrace, but the finale is not entirely quiet: Mrs. Andrews suddenly awakens from her coma and lunges at the couple with a knife, introducing a final jolt of danger as the night resolves into a tense, unsettled aftermath.
