Two orphaned brothers survive on the streets of St. Petersburg by stealing food and sleeping wherever they can find shelter. One winter night they climb into a railcar to escape the cold, only to wake up on a train carrying weapons to the front.

Their journey leads them to Osowiec Fortress, a remote Russian stronghold surrounded by marshland and war. What begins as luck soon places the boys in the middle of one of the most terrifying moments of the First World War.

Through the eyes of a twelve year old runner named Yuri, we witness the day a new weapon arrived at the fortress.

And the men who answered it.