Episode 2

Going behind the scenes of the world's oldest, largest and busiest underground train network as it undergoes the biggest overhaul in its history.

Every day, 60,000 journeys are made and not paid for, costing London Underground £20 million a year in unpaid fares. The programme follows Diane McConnell and Denese Brunker, two of the Tube's longest-serving ticket inspectors, and other plain-clothes revenue inspectors as they pursue fare evaders across the network.

Find what happens to the evaders and how the money from tickets is spent.