‘We think we’re good – but we’re weak’: the making of Natural Light, the year’s most harrowing film

To cast his gruelling war drama, Denes Nagy combed Hungary's farms for people with exhaustion in their face' - then shot it in the Latvian winter. The result? Awards, praise ... and fierce criticism

The publicist from the film company won't be able to make it to the hotel in Leicester Square to introduce me to the Hungarian film-maker Denes Nagy, whose gruelling slow-burn war drama Natural Light recent won him the best director prize at Berlin. But he emails to say that spotting Nagy shouldn't be too difficult: In the nicest way, he looks like the director of Natural Light." And it's true. There is a man in the foyer with an unmistakably auteur-like air: small wire spectacles, intellectual high forehead and a haircut he could have snipped himself in front of a mirror.

Natural Light is an unapologetically serious and beautiful piece of hardcore arthouse cinema. It's set in the Nazi-occupied Soviet Union in 1943 and follows a unit of Hungarian soldiers, allies of the German forces. Bleakly inscrutable and with very little dialogue, it's an intense watch. As one review put it, this is a film that makes demands on its audience".