The year is 1862 and Mexico is under the rule of Emperor Maximilian I. Ángel Montes, a well-known Juarista rebel, is captured by a group of renegade French soldiers who are eager to return to the power they once held under Maximilian's reign. Colonel Jean-Marie Leclère is the cruel commandant of a Mexican prison where Montes is being held. To save Montes, Confederate Major Jack Tanner assembles Confederate prisoners, but they soon find themselves caught in the middle of a bloody rebellion, and unsure of their loyalties. The group risks everything as they navigate a dangerous foreign civil war, spurring them to make a choice that might ultimately claim their lives.