The documentary follows the members of the Mara Salvatrucha, or commonly known as the MS gang. MS or Mara is a transnational criminal gang that started in Los Angeles, but has since spread to other parts of the United States.
The members of the gang distinguish themselves by tattoos covering the body and often the face. They also have their own sign language. When the gang was formed, the purpose was to protect Salvadoran immigrants from other and more established gangs of Los Angeles.
The gang has spread thanks to deportation. Many of the members have been deported after arrest, allowing them to recruit more members to the cause.
So, how hard is life in prison? Through the life of gang members, we can understand how inmates survive in prison. Life in prison is fight for survival. And every inmate has to find a way to survive. For many people, that weapon for survival is gang membership.