Five-year-old Saroo Brierley (Sunny Pawar) is separated from his dirt-poor family when he falls asleep aboard a train and finds himself 1,300 miles away in Calcutta. After scrapping a living on the streets, he's admitted to an orphanage where Nicole Kidman's foster mother adopts him. A couple of decades later, Saroo (now played by Dev Patel) sets off to find his real mum...with the help of Google Earth.
What with all the web conspiracy theories and privacy allegations flying about, poor old multi-billion dollar internet giant Google seems to have had little chance to live up to its corporate motto Don't Be Evil.
So this cockle-warming tale - about a lost child who rediscovers his remote Indian village decades later thanks to Google Earth - must come as a nice surprise.
The boy is Saroo Brierley, the son of an Indian peasant and single mom - who, while out with his brother - falls asleep on a stationary train and finds himself 1,300 miles away in the frantic hubbub of Calcutta.
Unable to speak the Bengali (his language is Hindi), Saroo - a tiny urchin banging into the legs of rushing commuters - desperately tries to make himself understood to a succession of indifferent adults.
Settling down for night among other waifs and strays, he literally gets a rude awakening from a gang of child-snatchers. After a narrow escape, he's taken home by a kindly housewife...who turns out no to be quite so kindly.
Eventually, thanks to the intervention of a charitable office worker, he finds himself in a government orphanage. But even here he's not safe...until he discovers all efforts to find his family have been exhausted and he's placed with an Australian foster family.
Twenty years later Saroo (now played by Dev Patel) is a handsome, thoroughly Westernised young man about to embark on a career in hotel management under the proud gaze of his new mum Sue (Kidman) and dad John (Wenham).
However, he still carries memories of his previous life and - at the prompting of his girlfriend Lucy (Mara) - sets about finding home with the help of fractured recollections (a water tower near a railway station) and the massive computer power of Google Earth.
With a story this strong, you can't really go wrong and director Garth Davis provides a sure guiding hand with Saroo's barely believable story unfolding largely in chronological order.
It's complicated by his relationship with his fellow foster brother Mantosh (Ladwa), a troubled young man who's never really recovered from his passage through the Indian social care system.
Kidman summons a brittle vulnerability as Saroo's empathetic mother but it's a poignantly sparkling performance from Sunny Pawar as the bewildered youngster terrifyingly at the mercy of the big city who really engages.
It's an uplifting tale - tempered by terrible revelation at the close - and proves to be that rate thing - a quality multiplex crowdpleaser.