Actor and investigative journalist Ross Kemp's award-winning documentary series focuses on the world's gang culture.

Each episode sees Kemp talking with gang members in a specific city, where he attempts to establish a relationship that leads to an interview with the gang's leaders. Also heard from are people who have been affected by gang violence, and the local authorities that are at times overwhelmed by the mayhem caused by the thugs.

The series has taken Kemp to the violent underworlds of such places as Rio de Janeiro, London, Moscow, Jamaica, Colombia, East Timor and Southern California.