Under Flag (1997)

Argentina: 1969: Major Molina has been sent to a military outpost in southern Patagonia to investigate the brutal murder of soldier Lito. The harsh weather conditions of Patagonia reflect the strict and cruel way in which the Colonel Hellman and his officers direct the garrison. Gradually comes to light that Lito was drugged by a fellow, Reppeto, and therefore was unable to participate in an unexpected military exercise at night. For his "disobedience", Lito was beaten to death. Molina seeks justice, aided by the deceased's family and the village priest. However, he is forced to abandon the case when the military forces take the power in Buenos Aires. Years later, with democracy finally restored in Argentina, the case will be reopened causing the abolition of military service and the military justice system.

Unfortunately the movie Under Flag is not yet available on HBO Max.