An American ex-marine, Lázaro Mendoza, enters a maximum security prison in Mexico (La Rotunda), under a false identity and accused of a supposed triple homicide. Now as Dante Pardo, his mission is to infiltrate inside a dangerous gang of prisoners and custodians that operates inside and outside the prison. They are the main suspects in the kidnapping of the teenage daughter of an American judge named John Morris. Within La Rotunda, Lázaro has to discover who is the mastermind of the kidnapping and find the whereabouts of the girl.