Year: 1979
Runtime: 115 min
Language: English
Director: Otto Preminger
A rookie Secret Service agent finds his idealism challenged when he unwittingly becomes entangled in a complex deception. His naivete is exploited by a skilled con artist, and when a trusted colleague is implicated in a suspicious scheme, he must confront the repercussions of his mistakes. Thrust into a dangerous game of cat and mouse, he desperately tries to uncover the truth and clear his colleague's name.
Warning: spoilers below!
Haven’t seen The Human Factor yet? This summary contains major spoilers. Bookmark the page, watch the movie, and come back for the full breakdown. If you're ready, scroll on and relive the story!
Read the complete plot breakdown of The Human Factor (1979), including all key story events, major twists, and the ending explained in detail. Discover what really happened—and what it all means.
Maurice Castle Nicol Williamson is a well-bred, mid-level bureaucrat in MI6 whose life seems unremarkable, apart from his African wife, Sarah Iman and son, Sam. The company regime, represented by éminence grise Dr. Percival Robert Morley and agency higher-up Sir John Hargreaves Richard Vernon, advise newly appointed security chief Daintry that analysis of intelligence from a double agent they have planted in Moscow indicates that there is a leak in Castle’s department. The info being shared with the KGB is trivial, but one never knows where things may lead.
The duo determine the mole must be identified and quietly eliminated, rather than be allowed publicity in a trial or defection to Moscow. They quickly decide the most likely candidate for the traitor is Arthur Davis Derek Jacobi, Castle’s red brick–educated playboy office partner.
Percival plants a seemingly tantalising intelligence tidbit with Davis, which he and Hargreaves assume will be passed on to the Soviets. Instead, unravelled by the intensive security scrutiny he is being subjected to, and utterly clueless why, Davis idly shares it with Castle. When the telltale bait shows up in Moscow, Percival concludes with myopic certainty that Davis was its source. An expert in assassinations and biological toxins, the doctor then injects a hungover, bedridden Davis with a toxin that makes it appear the man’s liver had given out from alcoholism.
Castle is given the task of hosting an old nemesis from his days being posted in apartheid South Africa seven years earlier: Muller Joop Doderer, the chief intelligence officer who had tormented him. Operating under his cover as a writer, Castle had been tasked by MI6 with observing the local Communist movement. He befriended its white leader, Matthew Connolly, who introduced him to the beautiful, sophisticated Bantu, Sarah. The couple fell for one another, and soon became intimate. Caught in a South African surveillance sting intended to compromise him into doing Muller’s bidding, Castle fled the country to avoid arrest and exposure, then awaited Sarah – pregnant by a previous, then-deceased boyfriend – being smuggled to him by Connolly.
Ever since then, Castle has been repaying the favour by passing information on to the Soviets via a contact in London, and flinches when Muller casually drops that Connolly had recently “accidentally” died in police custody. Shortly after, he learns in an agency briefing given by Muller of a plan for the South Africans to use U.S.-supplied tactical nuclear weapons to eradicate the nation’s Communist insurgents en masse. Although he is not a Communist, Castle feels compelled as a humanitarian to pass a warning on to Moscow, no matter the risk of shining MI6’s counterintelligence security spotlight on himself.
Seeking to stay one step ahead of Percival and Daintry, he surrenders himself into the hands of underground Communist operatives in Britain, who successfully smuggle him to safety in the Soviet Union. Having received assurances from his handler that his wife and child would soon join him there, he grows impatient when he learns that MI6 is preventing them from leaving Britain. Ultimately, a passport complication is arranged to force Sarah to choose between her husband and son.
Desperate, despondent, and isolated, Castle is reduced to a powerless pawn by the Soviets and forced to appear in a press conference both announcing his defection and denouncing the “Uncle Remus” nuclear ambush plan. The two worst fates of which he can conceive – losing his wife and child, and not only forfeiting his career and nation but being coerced into representing himself as both a Communist and a traitor when he never intended to be either – close in on him like the jaws of a vice. He is so overcome to hear from Sarah that she cannot, will not come, he is unable even to hang up the phone when their connection is lost. He collapses in anguish as its receiver swings like a pendulum from its cord, foreshadowing the approaching end of his rope.
Last Updated: October 04, 2025 at 10:30
Don't stop at just watching — explore The Human Factor in full detail. From the complete plot summary and scene-by-scene timeline to character breakdowns, thematic analysis, and a deep dive into the ending — every page helps you truly understand what The Human Factor is all about. Plus, discover what's next after the movie.
Track the full timeline of The Human Factor with every major event arranged chronologically. Perfect for decoding non-linear storytelling, flashbacks, or parallel narratives with a clear scene-by-scene breakdown.
Discover movies like The Human Factor that share similar genres, themes, and storytelling elements. Whether you’re drawn to the atmosphere, character arcs, or plot structure, these curated recommendations will help you explore more films you’ll love.
The Human Factor (1979) Scene-by-Scene Movie Timeline
The Human Factor (1979) Movie Characters, Themes & Settings
The Human Factor (1979) Spoiler-Free Summary & Key Flow
Movies Like The Human Factor – Similar Titles You’ll Enjoy
The Secret Agent (1996) Ending Explained & Film Insights
Rogue Agent (2022) Movie Recap & Themes
Agent Game (2022) Spoiler-Packed Plot Recap
Human Capital (2020) Ending Explained & Film Insights
Bad Company (2001) Movie Recap & Themes
The Double (2011) Complete Plot Breakdown
The Human Stain (2003) Film Overview & Timeline
All the Old Knives (2022) Ending Explained & Film Insights
Our Kind of Traitor (2016) Detailed Story Recap
Chief of Station (2024) Movie Recap & Themes
The Man with One Red Shoe (1985) Film Overview & Timeline
Traitor (2008) Ending Explained & Film Insights
Spy Game (2001) Ending Explained & Film Insights
Tinker Tailor Soldier Spy (2011) Story Summary & Characters
The Russia House (1990) Story Summary & Characters