Rob Bell has been granted special access to London's Tube network, where he'll uncover the story of how this engineering feat was achieved and the extraordinary characters that made it happen. We explore how the Tube's engineering innovations have shaped London; from its origins, to the building of the first true deep Tubes a hundred years ago, its pioneering maps, escalators, and its life-saving role during the Blitz. Rob reveals ghost stations, secret tunnels, hidden walkways, control rooms, depots, and repair pits. Rob walks through the tunnels at night time and travels through the maintenance conduits and serviceways by day. This series tells us about the Tube's history as well as how it's run today and the army of workers who keep five million commuters moving through the network every day.