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.
Transport for London investigators go on the trail of a fare dodger they suspect has avoided paying for more than 200 journeys. And officers board Hounslow trains - a hot spot for fare evasion.
The hunt is on in Surrey for a suspect thought to have evaded close to £20,000 of fares in one of South Western Railway's biggest ever fraud cases. And Harry has a run in with a barrier basher.
Investigators seek a fare dodger thought to be scamming Transport for London with over £5,000 in unpaid fares. And a man caught without a valid ticket proves uncooperative.
In Weston-super-Mare, new restrictions have provoked mixed reactions.