Until the real reason was revealed at the very end, we had two vague theories about why Lion was called Lion. The first was based on how uncannily leonine Dev Patel has become. The actor has a thick mane, a whiskery muzzle, a long handsome nose, and fierce eyebrows atop soft brown eyes. He’s undergone the Hakuna-Matata-montage-transformation that turned Jake Gyllenhaal and Aaron Taylor-Johnson from gangly teens to thick-set swaggerers. It’s a kind of second adolescence, courtesy of Hollywood, where swollen trapezoids signify a desire for roles that are correspondingly meaty.

Our second theory was that it might have something to do with the quote on the film’s poster: Lion will ‘rip you into a thousand pieces’. This seemed less likely; not because it’s a corny way to name a film, but because we remained emotionally intact throughout. Sure, there were some quite liquid-sounding sniffs coming from the seats behind us, and our eyes prickled slightly, but it wasn’t a spiritual mauling.

Lion is the feature debut of director Garth Davis, and based on the memoir A Long Way Home by Saroo Brierly. Saroo was born in India in 1981, where he lived in poverty with his mother and siblings. One day, aged about five, he accompanied his older brother on a journey for work and ended up alone on the wrong train – one bound for Calcutta, nearly a thousand miles from his village. Lost in a part of the country where most people speak Bengali (he had only a child’s vocabulary in Hindi), Saroo spent time on the street, sleeping rough and dodging human traffickers.

This section of the film is the strongest, and should be considered Davis’ calling card. He manages to convey Saroo’s perspective without sentimentality, balancing immersion with adult ironies through expert cinematography and very little dialogue.

The second half of the film is more rote. Eventually winding up in an orphanage, Saroo is adopted by an Australian couple (played by Nicole Kidman and David Wenham) and grows into Dev Patel. As a hale and wholesome Aussie bloke, Saroo is content with his life until a Proustian moment with some Indian street food triggers a need to find his way ‘home’. Involving obsessive use of Google Maps, his search complicates his sense of identity and his relationship with his girlfriend (Rooney Mara).

It would be easy to say that Davis couldn’t have done much better with a story about Googling, but there are traces of a much more intriguing film in a microscopic subplot about Saroo’s unhappy adoptive brother, another Indian orphan called Mantosh (Divian Ladwa). There’s a Zadie Smith-esque story there about the different fortunes of siblings, about globalisation and racial tension and mental illness; but it wasn’t Saroo’s happy, triumphant story, and it didn’t get told.