Tucson, Arizona, 1862. Eight Union cavalry and a scout from the 1st California Cavalry are conducting a sweep of the Picacho Peak area, looking for reported Confederates in the vicinity. The patrol lieutenant, Jeremiah, is an experienced soldier and a devout Christian, whose goal is to enter the seminary after the war is over. As the regiment continues to fall behind, the patrol's journey slowly becomes a struggle for survival, forcing the soldiers to reevaluate and make sense of their commitment to war.