In the mountains of Algeria, French army Lt. Terrien (Benoît Magimel) takes command of a platoon and is soon leading the men into a dangerous place called the Forbidden Zone, where Terrien's will is tested by the atrocities of war. Struggling to maintain his morality amid the torture and massacre of innocents, Terrien faces off against Sgt. Dougnac (Albert Dupontel), who asserts a more pragmatic approach to war.