This powerful documentary will be quite a shocker. Containing graphic evidence of the power and ruthlessness of the Brotherhood - "the most dangerous secret organisation in the US" - Jeremy Marre worked under extreme conditions, sometimes even at gunpoint, to make the programme. And as it unfolds, the documentary questions how society deals with men prepared to live and die by their own warrior code.

Snatched from their cells in maximum security prisons across America, some 40 members of the infamous Aryan Brotherhood gang were flown to fortress jails in Los Angeles. Twenty three of them faced the death penalty at the biggest case in US criminal history.

The most feared and deadly white gang in the US prison system, the Brotherhood stood accused of hundreds of beatings and killings; of intimidation, racketeering and drug dealing. Helped by an array of Federal forces, young prosecutor Greg Jessner used every trick in the book in an obsessive quest to bring the gang down.

By following a trail of drug deals, murders and hit notes disguised by invisible ink and secret codes, investigators revealed a unique criminal empire run from behind bars: one that controlled a major part of the prison system, and whose malign influence also reached over the prison walls, with killings and drug dealing taking place beyond the prison system.

Marre's determination to infiltrate the Brotherhood and to document its history is commendable. And his persistence bears fruit as he achieves unique access to the gang's leadership, acquiring secret videos of prison killings, beatings, riots and drug running.

Chilling stuff.