Inside the World's Toughest Prisons

Paul serves time in Piotrkow Prison, purpose-built in 2003 to contain the worst of the worst, where he meets a notorious gangland killer and learns how a zero tolerance regime has all but wiped out the Grypser prison gang.

Paul spends time in the overcrowded and impoverished Rizal City Jail, where he shares a cell with a convicted murder and a rapist. The ruthless Bahala Na gang rules another prison with almost military control.

In a television first, crime journalist Paul Connolly is granted access to El Hongo maximum security prison, one of Mexico's toughest jails from where no-one has ever escaped. Isolated in the barren Baja desert of northern Mexico, El Hongo is a concrete fortress of discipline and punishment designed to contain and control over a thousand inmates including hardened cartel gangsters.

Paul Connolly spends a week living inside Danli Prison in Honduras - where the inmates are in charge.

Investigative journalist Raphael Rowe spends a few days, both as a guard and a prisoner, inside Brazil's gang-filled Porto Velho Penitentiary.

Ukraine's Zhytomyr Prison is operated with a skeleton crew that allows prisoners to freely roam the grounds, often with potentially dangerous weapons.