After months of undercover work, the police in London start moving in their targets and claim their first victory against the hooligan mobs. But the celebrations are short lived. A new piece of science raises doubts over the evidence gathered as part of the police operations. Trials begin to collapse. The police and prosecutors are rattled and start scrutinising other cases yet to go to court. Dozens of cases are eventually dropped and fans previously jailed, have their convictions quashed. After 17 months working undercover among Arsenal’s firms, David is left holding his breath. Meanwhile, for Jim and Andy, the undercover officers in Birmingham, a chance encounter almost blows their cover and sees them running for their lives.

But with the police and politicians breathing down their necks, hooligans across the country are left looking over their shoulders. Is it time to walk away from the fighting and the firms once and for all?

Presenter: Tony Bellew