Revenue inspector Scott is on the lookout for fare evaders attempting to force their way through the ticket barriers. Alex and Baba join forces with the police in a sting operation along a busy stretch on one of the city's busiest bus routes.

Revenue inspectors Karen and Peter stop dishonest commuters exploiting a transport loophole.

A prolific barrier-blagger is handed an eye-watering bill for three years of illegal travel, while in east London, tube enforcement officers Karen and Peter stop passengers cheating with discounted tickets.

Undercover investigator Dan has a fresh case to crack at Kings Cross as someone pretends to `tap on' the ticket barriers with a declined debit card, before audaciously shuffling his way through the gates behind honest paying travellers.