Obsessed with MUSE, the clandestine project that created the AI in his brain, mercenary chief Durango draws the ire of the government when he steals part of the secret project data and hightails it with his lieutenant, Vienne, to an ancient monastery. There, he meets the monks who raised Vienne from an orphan and also encounters soldiers working for his old nemesis, the crime lord Mr. Lyme. Lyme controls the territory surrounding the monastery, as well as the datacenters housing the rest of MUSE. Undeterred, Durango and Vienne pull off an ill-advised raid on Lyme's complex. During the ensuing battle, however, Vienne is captured, and Durango is beaten and left for dead. Now, wounded and shaken, Durango must overcome bounty hunters, treacherous terrain, a full scale civil war, and a warrior monk with an eye for vengeance (not to mention his own guilt, self-doubt, and broken arm) to find Vienne and free her from Archibald, a brain-washing pyromaniac with a Napoleon complex who wants to rule Mars -- and kill Durango in the process.