21 Brothers tells the story of the Canadian 21st Battalion as they prepare for the battle of Courcellette in WWI. Taking place in real time, the film follows Sgt. Reid as he must get his men ready for the impending battle. Not only must he prep his battalion Sgt. Reid must also deal with the day to day difficulties of Life in the trenches, including injuries to his men, supply issues, and an underage recruit who has recently been sent into the front lines.

After an industrial disaster, the world's food and water supplies are contaminated. The rich and powerful retreat into fortified cities where life goes on, undisturbed by the starving masses outside their walls. While the outside world slides into unspeakable madness, Jacob, an idealistic citizen is on his way to the inner sanctum with others hell-bent on revolution when their train is attacked. Taking refuge in an abandoned house, he stumbles on a warlord's fortified cache of weapons and must fight for his life against humans turned savage. While desperately trying to hold onto his sanity, Jacob is forced into more and more heinous acts of torture and murder to keep himself alive.