Based on a well-known Polish novel with the same title the movie re-tells a true life story of a group of scouts called Szare Szeregi (Gray Ranks) during the Nazi occupation of Warsaw and the liberation of one of its members (imprisoned and tortured by the Germans) through a maverick military action in board daylight right under the enemys nose known Action at the Arsenal which was the biggest single feat of the sort undertaken by a youth resistance organisation in all of occupied Europe during WWII.