This time the fare evasion team are out scouring London's tube stations tracking down suspected persistent fare evaders. They are suspected of each racking up thousands of pounds in unpaid fares over long periods of time. Poised to pounce, the team study their movements via CCTV, devise a plan and finally approach the suspects in plainclothes.On the weekend of the Notting Hill Carnival, one of the largest street festivals in the world, around two million partygoers are expected to descend upon the west of the city. Teams are pulled in from all over London's transport network to help support the key stations.Keeping everyone safe and controlling passenger flow is the priority on the frontline, and at the network Control Centre they must keep a watchful eye over the millions joining the procession, and the rest of the network. But suddenly - could reports of a fire at King's Cross station have a devastating knock-on effect, as it inevitably brings back memories of the 1987 disaster…?