In east London, Karen and Peter run a sting operation to catch out passengers fraudulently using discounted travel passes, while Dan solves the case of a long-running scam at Southwark station. Amid the hustle and bustle of London's financial district, eagle-eyed inspector Scott is out to ensure that morning commuters are paying their dues.

A blagger gets an eye-watering bill for three years' travel.

Undercover detective Dan must outwit someone who is alleged to have fraudulently claimed refunds on hundreds of completed journeys, while a ticketless bus passenger threatens to get the police involved. At one of the London Underground's busiest interchanges, revenue inspectors Karen and Peter stop commuters from exploiting a transport loophole.

Revenue inspector Scott is on the lookout for fare evaders.