Four Sided Triangle

Four Sided Triangle

Year: 1953

Runtime: 81 mins

Language: English

Director: Terence Fisher

RomanceScience FictionMoving relationship storiesChilling experiments and classic monster horrorShow All…

Under his spell, a woman lives two parallel lives. As children, Lena, Robin and Bill are inseparable, but years later Lena returns home and falls for Robin. Obsessed, Bill perfects a duplication technique to create an exact copy of the woman he cannot have, leading to tragic consequences for all three.

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Four Sided Triangle (1953) – Full Plot Summary & Ending Explained

Read the complete plot breakdown of Four Sided Triangle (1953), including all key story events, major twists, and the ending explained in detail. Discover what really happened—and what it all means.

Dr Harvey, an old rural physician, breaks the fourth wall to relate an unusual occurrence that happened in his village. The bulk of the story unfolds through a long, reflective flashback, guiding the audience through a blend of quiet countryside life and a radical scientific experiment. The tale centers on longing, loyalty, and the strange consequences that arise when invention steps into human hearts.

Bill and Robin are boyhood friends who compete for Lena’s affections. Lena’s family moves away, and as adults the two men become scientists. They set up shop in an old, abandoned farmhouse, where their collaboration centers on the Reproducer, a device capable of exactly duplicating physical objects. The project draws them into a shared obsession, a project that promises to redefine ownership and identity while testing the limits of friendship.

Years pass, and Lena returns to the village. The reawakened feelings between Bill and Robin flare anew, threatening to pull them away from their work. In time, the friends abandon the Reproducer, and Robin leaves the village to learn his family’s business. Bill is left to grapple with the discovery that Lena loves Robin and intends to marry him, a realization that fuels a stubborn resolve to win her back at any cost.

Hoping to secure Lena’s affections, Bill persuades Lena to let him use the Reproducer to create a duplicate of herself. The experiment succeeds, and the new copy is named Helen. As a perfect double, Helen also falls in love with Robin, creating a dangerous triangle where affection, loyalty, and science collide. Bill believes that electric shock therapy could erase Helen’s knowledge of Robin, and Helen, believing she has little chance with him anyway, agrees to undergo the procedure. Lena agrees to help with the plan, and the old farmhouse becomes the site of the clandestine operation.

The process proceeds as planned, but disaster strikes: the apparatus overheats, explodes, and plunges the farmhouse into a terrible fire. Robin and the doctor arrive just in time to rescue a figure from the blaze, but Bill and the other woman perish in the inferno. Harvey, who has been briefed by Robin, learns that the rescued woman has amnesia. The two men wonder which woman they have saved, a question that hangs in the air as the fire dies down.

Harvey recalls that Bill had to start Helen’s heart with a device attached to the back of her neck, leaving two small scars. When the smoke clears, Robin is relieved to find that there are no marks on the neck of the woman they saved—she is Lena, the woman Robin loves and who is safely with him at last.

Last Updated: October 09, 2025 at 11:21

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