A day-long look at that vast undertaking, London Transport, and at all those - commuters, shoppers, excursionists, theatregoers, and the rest - who rely upon it. This is a film about London as seen by London Transport. Starting at dawn we see the slow build-up to rush hour and afterwards the mid-morning lull. The scene changes to Saturday afternoon, the hurly-burly of sport and pastime, then on to the evening gaiety of the West End, while below the surface men are tunnelling the new tube line from Victoria to Walthamstow