Across the world millions of people are members of street gangs. In groups they fight, stab, rob, rape and murder anyone who isn't one of their own. And when rival gangs meet – what you get is warfare.Ross Kemp, whose dad was a copper and taught him right from wrong, decided to infiltrate these secret underworld organizations to discover who they are, what makes them tick and what the law is doing to curb their criminal activity. On his harrowing journey he: meets murderous members of the Number gang in a Cape Town jail crosses paths with warlords in Guatemala gets shot at in El Salvador is set on fire as an initiation test for Russian Neo-NazisOnly TV hardman Ross Kemp could get this close to the world's most violent street gangs: he's tough enough to earn their trust and so get them to confide their innermost secrets. It's a wild ride – and not for the faint hearted.