El Salvador has colonial architecture and beaches but almost no tourists, because between 3,000 and 6,000 people are murdered there each year in a population of just 6 million. This film goes inside the decades-long war between MS-13 and Barrio 18, the two gangs, or maras, that have carved the country's neighborhoods into hostile territory since the 1990s. Julio, a Barrio 18 leader, lets cameras film the induction ceremony for a new recruit, and Zorro, a hitman who describes some of the gangs' worst killings, speaks on camera about his role in the violence. With government authorization, the crew films inside the high-security prison of San Francisco Gotera, where 1,700 gang members live in crowded, deplorable conditions, undergo daily evangelical religious programming, and are forced to share cellblocks with members of rival gangs they were once ordered to kill. The result is a direct, unflinching look at gang life from the inside, told by the people who built and enforce it.