Find out what goes on inside America’s most dangerous prisons. Visit the institutions where hardened criminals try to break all the rules every day and meet the prison officers who try to keep them in line.

Discover the stories behind the inmates who are kept there. For some, life on the inside is all they know. For others, only thoughts of their loved ones keep them on the right track. And for those who want to go straight, their biggest challenge comes when they try to make a new life on the outside.

There are as many people incarcerated in US prisons as there are residents in Brisbane. Plunge head-first into the gritty world of America's most dangerous prisons where gangbangers and hotheads face off with prison officers struggling to maintain order. Only the strong survive here.