Part one of two. The documentary maker goes inside the walls of HMP Belmarsh, the country's most notorious maximum-security jail, which has housed the country's most dangerous - and infamous - convicts, including Ian Huntley, Ronnie Biggs and Charles Bronson. Ross explores how staff cope with high-profile inmates, extremists and common criminals living side-by-side and goes inside the High Security Unit, where he meets Muhammad Asif Hafeez, known as Sultan, the alleged mastermind of a drug-smuggling empire.