Nazi-occupied Bosnia and Herzegovina in 1943. Under the faithful leadership of Marshal Tito, the Yugoslavian partisans have put up a staunch fight against the occupying Axis powers for a number of years. Despite being outgunned, outmaneuvered, and vastly outnumbered, they managed to recuperate in the harsh mountainous region called Durmitor in northern Montenegro. However, their rest was short-lived, as the combined foreign and domestic Axis powers begin an encirclement offensive, outnumbering them 6:1. The Partisans have no choice but to fight out of the encirclement, heading towards eastern Bosnia. They finally clash with the Axis on the plains of Sutjeska in southeastern Bosnia.

Various people are caught up in the fighting, such as a Dalmatian who lost all of his children during the war. As the fighting intensifies, the story and the scenes are drawn more and more into the colossal battle as both sides are forced into a conflict that can only be described as a living hell. The scenes are interlaced between general battle rage and individual, personal fates and agonies of several main characters, from supreme commanders to ordinary soldiers.

The offensive finally ends as a failure for the Axis armies, but the Partisans are not in a mood to celebrate — they suffered devastating losses. Still, they marched on.