Over a billion passengers a year. And 19,000 employees. All facing a daily battle with the world's oldest subway system: the London Underground.
This documentary provides a rare glimpse into the depths of the iconic Tube network that passengers don't see, as workers reveal the dilemmas and pressures that they must reconcile to keep this hugely complex and strained system running.
Actors voice the precise words of the workers: train drivers, maintenance workers, station staff and controllers.