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.

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. Revenue Protection officers Michelle and Lucky expose short farers at Vauxhall. And at London Waterloo, Jack and Jack face up to an explosive passenger, while Harry has a run in with a barrier basher

Investigators go on the trail of a fare dodger they suspect has avoided paying for more than 600 journeys and officers monitor Hounslow trains, a hot spot for fare evasion.

Transport for London investigators Rich and Greg are on the trail of a man they believe has run up more than £1500 in unpaid fares in east London on the Elizabeth Line. At Waterloo, South Western Railway revenue protection officers Ty and Jack chase a barrier jumper, while Sharon and Carlos set up enhanced checks on the barriers at Weymouth after multiple reports of disorder and chronic fare evasion

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.

Investigators trail a man they believe has racked up nearly £2,500 in unpaid fares by fraudulently making contactless payments with his bank card.

At Vauxhall, revenue protection officers from South Western Railway are involved in a major sting operation which prompts an investigation into fraud going back seven months. A lady is stopped using a half-price ticket bought with a Job Centre Plus discount card which she doesn't have. At Southampton, Spencer is on high alert after claims that two young women who push through the barriers are being abusive and are trying to travel for free. At Waterloo Harry takes on tailgaters and the abuse of half-price child tickets at half term. And two newly trained recruits are on the Weymouth to London line - a route notorious for fare dodgers.

At Clapham there's a major operation to clamp down on fare evasion. Nathan and Dan tackle an epidemic of ticketless travel between unstaffed stations.