Following Transport for London's revenue protection teams, highlighting the work of frontline enforcement officers and undercover investigators fighting against the estimated 125,000 passengers who dodge fares across the city every day. Investigators go on the trail of a fare dodger they suspect has avoided paying for more than 200 journeys and officers monitor Hounslow trains, a hot spot for fare evasion.

Investigators Rich and Greg go on the look-out for a fare dodger thought to be scamming Transport for London for over a year, racking up more than £5,000 in unpaid fares. At Waterloo, South Western Railway revenue protection officer Sam faces a tense situation with a man caught without a valid ticket who is more focused on finding a toilet than co-operating.