For the first third of this film, you would be forgiven for thinking you were back under the influence of the Italian neorealists: largely non-professional actors in a realistic milieu; themes of poverty and deprivation; a child at the centre of the action. That it takes place in India only heightens the effect; it is difficult to conceive of a contemporary setting more dangerous or overwhelming for a lost boy than teeming Kolkata. Or Calcutta, as it was known when Saroo (Sunny Pawar) arrived by train in 1984, having accidentally left his family thousands of miles behind in a town he was too young to name.