This steely, sinister and utterly gripping movie is the feature debut of 28-year-old actor-turned-director Brady Corbet. It’s an inspired provocation, jabbing its audience with a fictional variant on history, and loosely based on Jean-Paul Sartre’s 1939 short story of the same name. Corbet has co-written the screenplay with his partner, film-maker Mona Fastvold.

The film imagines the wealthy, dysfunctional and unhappy childhood of someone fated to become a fascist leader: the action, disturbing enough in any case, is retroactively charged with this poisonous destiny. Newcomer Tom Sweet plays Prescott, the unhappy 10-year-old son of an American career diplomat (Liam Cunningham), who is in France in 1919 as part of US president Woodrow Wilson’s retinue, there to establish postwar settlement terms to be imposed at Versailles on the defeated Germans. His beautiful and troubled wife (Bérénice Bejo) has effectively got her husband the job because she is a fluent French speaker, though he is not.

Stacy Martin plays Prescott’s tutor; she is becoming this lonely, unhappy boy’s only friend. His father’s only friend is a journalist and free-thinking intellectual, elegantly played by Robert Pattinson. With a clever flourish, Corbet also creates a second role for Pattinson to play. In this troubled household, Prescott comes to see what power is.

Versailles, of course, calls to mind just one “leader”: the one whose career was based on persuading Germans they had been humiliated and betrayed by the surrender terms of the first world war. But Hitler’s childhood – and Mussolini’s, and Stalin’s – were much more lower class than the one shown here. Franco was a bit higher up the scale. The fascist leader who compares in patrician entitlement and privilege is Oswald Mosley, and even he doesn’t quite fit. Fascinatingly, it is a more metaphorical origin myth about American as much as European fascism.

Prescott himself is a petulant princeling-sociopath who looks a little like Damien in The Omen, and pretty Tadzio in Visconti’s Death in Venice: he is always being mistaken for a girl and refuses to cut his hair. He is also like Anna, the doctor’s daughter in Michael Haneke’s The White Ribbon, that unsettling parable about the childhood of a leader’s entire country.

Bérénice Bejo in The Childhood of a Leader. Photograph: IFC Films/Everett/Rex Shutterstock

The roots of Prescott’s unhappiness – and, therefore, perhaps the roots of 20th-century fascism – are sexual. Corbet’s story has a rather Russian, Turgenevian slant. He is infatuated with his tutor: we see him mesmerised by the sight of her nipple as she reads to him from Aesop’s fables. But one afternoon he walks into the dining room and is baffled to find this tutor in intimate conversation with his father, who looks up sharply. At their excruciatingly formal family dinner later, he asks him if he is taking French lessons; the father blusters an obviously unconvincing explanation, and his mother humiliates herself by face-savingly confirming the excuse that all three know is nonsense. The lie causes Prescott to retreat into tantrums, which the aged kindly servant (Yolande Moreau) defies his parents by indulging – so she has to be dismissed. Is her sacking the leader’s “Rosebud” moment? Prescott learns that the brutal imposition of power is the response to unhappiness, while his father prepares to impose power on a whole continent.

The Childhood of a Leader is structured around Prescott’s tantrums: a conceit that might bring to mind Hitler’s creepy diplomatic practice of pretending to be very angry, while not really being angry at all. This young leader is growing up in a world where all of the adults are telling him about the importance of rejecting anger, embracing forgiveness. The local priest gives sermons on this theme, and Prescott’s tutor makes a deep impression on him with the Aesop fable about the virtues of gentleness in power; the lion who befriends a humble mouse. Yet Prescott can see that power is actually working in quite another direction.

It’s a film that exerts a lethal grip, assisted by a clamorous, almost Herrmann-esque orchestral score from Scott Walker. The touch of suppressed psychopathic rage comes from his music. Corbet himself, in talking about his film, has invoked Dreyer. A bit hubristic, that, but not completely out of line, and if Corbet has taken something from that director, he’s done so with intelligence. It might be considered arch for a young first-timer to release a movie with this title, but Corbet has earned the right to be precocious. What an exciting debut.