Year: 1979
Runtime: 100 mins
Language: English
Director: Robert Day
An intricate whodunit follows a celebrated mentalist whose unfaithful wife schemes to frighten him to death, while the family’s loyal confidant and the wife’s ham‑actor lover become entangled in the plot. The story blends adult drama with relentless twists, offering a literate, puzzle‑like mystery.
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Read the complete plot breakdown of Murder by Natural Causes (1979), including all key story events, major twists, and the ending explained in detail. Discover what really happened—and what it all means.
Arthur Sinclair, Hal Holbrook, is a highly successful mentalist who preys on affluent socialites, weaving charm and manipulation to secure their wealth. The film opens with him on the phone, bidding farewell to his much younger wife, Allison Sinclair, Katharine Ross, who pretends to wish him well as he heads off to a television interview. In truth, Allison lies next to a younger, ambitious lover, Gil Weston, Barry Bostwick, a would-be actor who has fallen for her and hopes to ride the intrigue of Arthur’s world into his own fortune. This precarious arrangement sets the stage for a night that blends danger with desire, as Allison hatches a plan to have Gil scare Arthur into a fatal heart attack by staging a home-invasion.
The setup unfolds with meticulous calculations. Gil enters the Sinclair home under the guise of a journalist seeking an interview, and the two men—Arthur and Gil—engage in a tense, almost cordial dialogue that exposes hidden agendas on both sides. Gil already knows that Arthur isn’t a real journalist, while Arthur recognizes Gil as a pawn in a broader scheme. To test Arthur’s limits, Gil taunts him, pushing him to perform fifty push-ups to tire out his reputedly fragile heart. The evening escalates into a perilous game of cat and mouse, culminating in a struggle during which Gil seemingly lies dead at Arthur’s hands after a gun is drawn and fired. When Allison returns to the scene, she confronts the aftermath with a mix of dread and relief, but the danger is far from over.
What follows is a chilling reversal that reveals the depth of Arthur’s manipulation. Arthur has long known about Allison’s affair with Gil and considers the entire arrangement a way to expose and control the people around him. Into this tense mix steps George Brubaker, Richard Anderson, Arthur’s lawyer and longtime friend who turns out to be Allison’s true lover. George’s entrance confirms that Gil was never the mastermind; he was a disposable instrument used to lure Arthur into a trap. In a brutal turn, George shoots Arthur, and he and Allison depart, thinking the danger has passed. Yet Arthur’s cunning does not end with his supposed death: later, Allison returns to the house and discovers that Arthur’s body has vanished. It is revealed that Arthur anticipated the danger and took steps to survive by substituting all the bullets in the gun with blanks, a detail that shifts the power dynamic entirely.
The twist deepens as Arthur re-enters the scene—this time with the leverage of altered odds and a mind that remains several steps ahead of everyone around him. With the body missing and the threat of real bullets looming, Arthur now faces Allison directly. The tension between them is charged with history, power, and a dangerous chemistry that keeps the audience guessing about who is truly in control. As the confrontation comes to a head, Arthur lowers the mask of the gentleman mentalist and turns his attention to the ultimate test: trust, fear, and the possibility that he has the final say in how far love—and danger—will go.
In the end, the film pivots on a stark, chilling line that encapsulates the calculated cruelty that defines Arthur’s world. Facing Allison once more, he lets the weight of his experience settle over the moment and delivers a blade of skepticism wrapped in a chilling invitation. “I have a suggestion for you, darling…why don’t you read my mind?” The line lands as more than a taunt; it’s a declaration that Arthur’s mental prowess remains unbroken, and that the game between predator and prey may be more about intellect and control than about physical force.
Throughout the story, the pace is deliberate, the stakes are personal, and the psychological tension is the true engine of the plot. The relationships among Arthur, Allison, Gil, and George form a web of deception that unfolds with calculated precision, revealing how easily appearances can mask danger in a world where wealth, glamour, and ambition blur the lines between ally and adversary. The film maintains a cool, measured tone as it navigates themes of manipulation, trust, and revenge, allowing the twists to arrive with a quiet, almost clinical inevitability that keeps the audience riveted while never losing sight of the characters’ core vulnerabilities and the dangerous games they play.
Last Updated: October 09, 2025 at 10:52
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