Ross Kemp and his award-winning team continue to seek out the world's most notorious gangs, gaining rare access to notoriously impenetrable mobs. From Jamaica to Poland, Colombia to East Timor, Ross infiltrates these terrifying street gangs to discover who belongs to them, what drives them and what the law is doing to curb their activity.

'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 he 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 employment 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.