Jamaica boasts the highest murder rate in the world. Ross investigates the two Yardie gangs at the heart of the killings; with 10,000 members between them.

Ross travels to Poland to visit the 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 Gorzów, to meet the leaders of the brutal Stilon Fighters.

For decades Colombia has been embroiled in civil war as paramilitary and guerrilla forces fight for control. What isn’t widely known is the part gangs play in this conflict and Ross meets with the most secretive of them all, the Sicarios.

East Timor's Sacred Heart and Seven Seven gangs have brought the country to the verge of collapse. More than two-thirds of Timorese youth are believed to be involved in gangs. Crude and, at times, primeval, members undergo bizarre initiation rituals where roots are implanted in their chests to make them believe they are invincible. Ross travels with the United Nations peacekeepers as they witness this youthful nation's descent into anarchy.