During the invasion of Parthia, two Roman legions have been brought to a standstill in the snowy mountains of Armenia, leaving them slowly dying in the freezing cold. The rest of the Roman army is two weeks' march away, and the region swarms with Parthian patrols. Their only hope for survival is Noreno, a half-Roman soldier, who is entrusted with the impossible mission of crossing the deadly terrain to save two legions.