Synopsis of this episode.

The documentary follows the overnight maintenance workers who descend on the London Underground during a four-hour window when the trains stop running. Among the 10,000 members of staff who work against the clock to get the network ready for the following day are 23-year-old Harry, whose team picks fibres and lint from the tracks, and Bulgarian cleaner Vladimir, who shares his opinions on government policy. Plus, pest controller Mick is called called to a smelly problem at Hounslow Central. Last in the series