It is the thing you have half-imagined, could scarcely believe, possibly had nightmares about. Son of Saul brings us close – as close as cinema will ever get – to the dragon’s mouth of the Holocaust. This is a vision of Hell reminiscent of Bosch and Goya, indelible and obscene, yet without the distancing of allegory: it is specifically a Hell on Earth, Auschwitz-Birkenau, October 1944.

Hungarian director László Nemes plunges us in medias res. Amid scenes of chaotic dread, a young man, Saul (Géza Röhrig), herds Jewish prisoners from a train platform towards the promise of a shower and food – in fact, they are bound for the gas chamber. Once the doors close and screams rise up he must begin sorting through their clothes for valuables (“gold, coins, whatever you find”).

Saul, a Jew himself, is part of the Sonderkommandos, teams deputed to do the Nazis’ dirty work, tending the furnaces and scrubbing the floors for the next slaughter. A red X is crudely daubed on the back of their jackets, like a target. As a “bearer of secrets” he and his kind have only a few weeks’ stay of execution before they too are dispatched.