The Mexican village of San Patricio is being menaced by a bizarre, cultish, and notoriously brutal drug cartel. As the townspeople try to defend themselves by forming a vigilante group, the Mexican army and police have their own ways of fighting back. Into this volatile mix of forces for good and evil steps Timothy Riordan, an American missionary priest who must decide whether to betray his vows to help the people he has pledged to protect. Riordan's close friend and fellow expatriate Lisette Moreno serves the region in a different way, as a doctor who makes "house calls" to impoverished settlements, advocating modern medicine to a traditional society wary of outsiders. To gain acceptance, she must hide her rocky love affair with a troubled artist who is also a woman.Together, Lisette and Riordan tend to their community. But when Riordan oversteps the bounds of his position, his personal crisis echoes the impossible choices facing a nation beset by instability and bloodshed. Based on actual events.