The film is set in 1959 during the Algerian War. Lieutenant Terrien (Benoît Magimel), an inexperienced and naïve junior French Army officer, has volunteered for active service, rather than a safe staff post in Algiers. He is posted to Kabylie, a remote and mountainous region of Algeria, as a replacement for Lieutenant Constantin (Hicham Hlimi) who was killed during a ‘friendly fire’ incident commanding a counter-insurgency ambush operation – i.e. he was accidentally killed by his own side during a confused fire-fight. The war in Algeria is much more complicated than Lieutenant Terrien anticipated as he takes over command of his new platoon at the outpost "Mazel". Within hours of taking over his new command Terrien is ordered to lead a ‘locate and destroy’ mission into the ''zone interdite'' (the 'Forbidden Zone') to find a World War II French Army veteran named Slimane, now a local commander of Algerian rebels trying to win the independence of their homeland. Slimane is never seen in person during the film.