Ross Kemp and his award-winning team seek out the world's most notorious gangs, gaining rare access to notoriously impenetrable mobs.

'El Salvador' - Ross travels to this tiny country of earthquakes, volcanoes and gun rule to find out how MS13, considered by the Americans to be 'the most dangerous gang in the world', operates. He meets leaders of MS13 as well as the foot-soldiers, those gang members living in such perilous surroundings that the bottom of their road is a no-go-zone.

'Cape Town' - South Africa's ferocious Numbers gang thrives in the country's overcrowded prisons. Nowhere is their power more potent than Cape Town's Pollsmoor High Security Prison. Here, Ross learns the fearsome power of the Numbers who subject new arrivals to violent attacks and gang rapes as part of their brutal initiations.

'St. Louis' - St. Louis is home to one of America's most active and aggressive gang cultures making it one of the five most violent places in the US. Here Ross meets families dealing with gang violence, a man trying to leave gangster life behind him, and the police who are trying to deal with this culture.

'Moscow' - Ross Kemp gets inside Moscow's vicious Neo-Nazi gangs and discovers who is behind the recent racist attacks. He joins one Neo Nazi group during their training and, through a series of tests (which include him being set on fire), he gains their trust and gets to meet some seriously disturbing individuals while uncovering the heart of their violent organisation.

'Jamaica' - In Kingston, the murder capital of the world, gangs were historically aligned to Jamaica's two political parties. Ross discovers the gangs have moved away from their political roots and now engage in a bloody turf war, funded by drugs and driven by tit-for-tat reprisals, that has spawned a new generation of even more violent gangs.

'Poland' - Polish Neo-Nazi football hooligans have become some of the most feared gangs in Europe. Ross joins an elite police riot squad as they escort a notoriously violent hooligan gang and travels to Gorzow, a depressed and forgotten town, to meet the leaders of the brutal Stilon Fighters.

'Colombia' - In a country ravaged by war and synonymous with drugs and violence, Ross meets the people involved in the long and bitter guerrilla fighting - including the most secretive of them all, the Sicarios. These small groups, mostly under the employ of the paramilitaries, operate as 'hit-squads', killing whoever is considered a threat.

'East Timor' - More than two-thirds of Timorese youth are believed to be involved in gangs, ranging from martial arts groups to cult-like animist gangs. In the barrios of downtown Dili, Ross meets Sacred Heart and Seven Seven, two gangs in the midst of a deadly conflict, and witnesses their bizarre rituals, strict training and terrifying arsenal.