Underground is the name of a film by Emir Kusturica which won the Palme D'Or at Cannes in 1995 and subsequently did so badly at cinemas worldwide, despite critical acclaim, that Kusturica declared that he would never make another film. Part of its unpopularity must have come from its length (roughly 3 hours) and its style (surreal and fantastic), as it is an astounding experience emotionally and cinematically.
Its main theme is the exploration of the upheavals that have wracked the former Yugoslavia from the second world war until around the time of its fragmentation into smaller states. Instead of focusing on the outward social changes and wars, it follows a group of Yugoslavian rebels during WWII who are hiding in an underground bunker. Their compatriot in the house above them doesn't tell them when the war ends, keeping them in the bunker by producing regular air raid sounds and feeding them 'news' of the world above, while they make him rich by making weapons and ammunition which he sells.
As one might expect, the film addresses issues of war and betrayal through surreal events and powerful images rather than rational discussion. One of the most disturbing and powerful moments comes when the hero, Blacky, sets his friend (who betrayed them) on fire in his motorized wheelchair, which proceeds to career blazing in circles around Blacky, who is beating his forehead off a stone column in despair.
The film also explores issues of truth and fiction in a much lighter way, such as when Blacky and his son attack a crew who are shooting a scene from a Nazi film, mistaking them for real Nazis because, of course, they don't know yet that the war isn't over.
Somehow, as in Arizona Dream, Kusturica manages to give the viewer a powerful sense of empathy with characters who are more than mildly unhinged and divorced from reality, by showing that no matter what craziness they are involved in, or what their emotional pain makes them do to each other, they are full of tenderness and sorrow and laughter like all of us. At the end of the film, the dead characters are seen drifting away from shore on an island which represents the Yugoslavia they once knew, which no longer exists except in dreams and art and memory, the human acts of preservation which we can all understand.