Dara Maren is a DEA agent who gets dragged into the seedy underworld of California/Mexico border smuggling in an attempt to protect her younger brother. During a drug deal gone bad, she ends up shooting and killing an undercover ATF agent and is arrested. She's convicted and incarcerated inside a penal colony just outside Tijuana, where the prison officials harvest organs from the inmates. During her incarceration, Dara's brother is murdered by a drug lord who's also using human spinal fluid drained from his victims to create a new DNA-altering drug that turns those who become addicted to it into something not human. As hundreds of dead bodies start turning up along the Mexico border, and with law enforcement and government officials falling victim to its addictive properties as well, an old friend from the FBI manages to bribe the officials in Tijuana to let Dara back out onto the streets in order to bring down the drug lord and avenge her brother's murder.
In Mexico in 1895, Clementine Templeton is obsessively tracking the wanted man known as Sentenza for deserting her and their infant child. In her travels, she happens upon a gang of former prostitutes led by Mary Black, whose young daughter was also impregnated and abandoned by Sentenza.
They eventually locate their prey and corner him in a remote ghost town called Amnesty. Which is haunted by the vengeful ghost of slain preacher Mobius Lockhardt, who has made a pact with the devil to remain as an earthbound spirit unable to travel beyond the borders of the town's cemetery and slaughtering any who trespasses.
But there are many secrets surrounding the group and the town of Amnesty, and not everyone's motives are what they appear to be on the surface. As bloody betrayals and misdeeds come back to haunt them, they must confront their pasts if they hope to escape Amnesty and the vengeful wrath of Mobius Lockhardt alive.