Series 1

Episode 1 (Weekend) highlights the difficulties of undertaking major renewal of the tracks without disrupting the weekday service, the engineer works at Harrow-on-the-Hill station which results in no Metropolitan Line nor National Rail services at the station until the completion of the engineer works, and the handling of an incident at Leicester Square Station where a woman was pushed onto the electrified tracks at Platform 4, resulting in huge crowds, an arrest (although the suspect was later released without charge) and Northern Line services from North and Southbound trains having to pass without stopping until the closing of the station when the Northern Line was suspended at Leicester Square.^[6]

Episode 2 (Revenue) looks at the work of ticket inspectors and others working to track down the estimated 60,000 people who use the system each day without paying for a ticket, which costs the Underground some £20 million in lost revenue each year. The episode also includes two ladies who are the ticket inspectors for the Northern Line, and two men keeping a lookout for any Oyster card system problems on the Hammersmith and City Line at Latimer Road. The Metropolitan Line makes a change as the A Stock train is replaced with a brand new S Stock Train and both lines, as well as the Circle Line, are suspended from Liverpool Street when a track failure occurs at Farringdon.^[7]

Episode 3 (Emergency Response) looks at the trauma caused to drivers when passengers fall or jump in front of a train. It also looks at the work of the emergency response unit at Bank and Euston Stations where, in both cases, the passengers were fatally injured, and the types of incident that the unit has to deal with. It also shows the stresses put on the system by the Notting Hill Carnival, as well as some plans for the crowds at both Notting Hill Gate and Westbourne Park stations where 42 arrests have been made without any serious incidents.^[8]

Episode 4 (Upgrading the Tube) looks at reliability issues following the introduction of new trains on the Victoria line and the knock-on effects caused by the failure of a newly installed signal. It also shows the work of a station supervisor at Tottenham Court Road as he tries to ensure that customers are kept moving during an upgrade to the station which will increase its size by a factor of six, resulting in the Northern Line having to pass TCR without stopping for 7 months until the upgrade is complete.^[9]

Episode 5 (Rush Hour) covers Bank station, where five passengers suffered from fainting or injury during a single rush hour shift, and problems on the Jubilee line when a failure of the power supply almost disrupted the evening peak services. It also shows the use of a hawk called Toyah to clear train sheds of pigeons.^[10]

Episode 6 (Overnight), the final episode, which aired on 26 March 2012,^[5] featured the work of cleaners, who work during the four-hour period each night when the power is switched of, to clean the stations and remove lint and fibres from the tracks to reduce the risk of fire. Other stories included the work of a pest controller at Hounslow Central, and a visit to the disused Down Street by a member of the emergency response team.^[11]