There are some noticeable gaps in the story’s logic, but generally this is a powerful prison film supported by strong performances from Luis Tosar and Alberto Ammann. The latter, playing "Juan," is touring a maximum-security facility when a major riot erupts, spearheaded by "Malamadre" (Tosar). It was pure chance – he'd been injured previously and was recuperating in cell 211 – that prevented him from being taken prisoner along with two of his future coworkers. He’s resourceful and, because he happened to be covered in blood, manages to persuade their supervisor that he is simply another new arrival. However, it’s clear he's walking a precarious path; not everyone trusts him, and as serious negotiations start, he realizes it will become increasingly challenging to de-escalate the situation and survive. Simultaneously, those in charge are handling things poorly outside, which results in a disastrous event that forces "Juan" to completely re-evaluate his allegiances. The film’s strength lies in its sharp dialogue and intense visual style. It is certainly violent and angry, but these prisoners are also portrayed as victims; their complaints about the harsh conditions of solitary confinement have been ignored for so long, and this action represents a final attempt at being heard – just inquire with the previous occupant of cell 211! Tosar delivers an impressive performance as a more refined criminal, and as the two men collaborate, a connection develops that may ultimately be what keeps them all alive.

Source on TMDB