Only the most shrivel-hearted grinch could watch this Christmas release and not be moved. Based on actual events, Lion chronicles the odyssey of Australian businessman Saroo Brierley, who was born in India. It's an affecting meditation on identity, home, family and fate. Be forewarned: There will be tears.

The feature debut from director Garth Davis, the movie is divided into two chapters. The first takes place in 1986 in the impoverished village of Ganesh Talai. There the young Saroo is played by an irresistible first-time performer named Sunny Pawar. He's this year's Jacob Tremblay (Room), a total natural and miniature marvel.

Saroo lives in squalor with his mother (Priyanka Bose); younger sister, Shekila (Khushi Solanki); and older brother, Guddu (Abhishek Bharate). The family is the poorest of the poor. His mother lugs rocks for a living. The boys help out by committing urchin crimes. In an early scene, the two gleefully cling to a moving train, stealing coal they can trade for milk in the street market. Barely 5, Saroo is eager to prove he can do anything Guddu can.

This desire leads to the defining event in his life. When Guddu tells Saroo he'll be away for a week working in the fields, Saroo pleads to come along. It's night by the time they reach the train station, and the younger boy is asleep. Guddu has no choice but to briefly leave him lying on a bench. "I'll be back," he says with a smile. "Don't go anywhere."

When Saroo awakes, he's alone on the platform and instinctively seeks shelter in the nearest train. He locks himself in a decommissioned passenger coach, and the next thing he knows, it's hurtling across the country. There's nobody to hear his cries for help.

When the train stops, the boy is 1,000 miles from home on the mean streets of Calcutta and unable to communicate. He speaks Hindi. The masses swarming about him speak Bengali. For months he survives on garbage scraps, and, more than once, he barely slips through the fingers of traffickers. Veteran cinematographer Greig Fraser (Zero Dark Thirty) effectively captures the dread and menace infusing the dusty, dark underworld that Saroo inhabits.

This India is the opposite of the happy, colorful one depicted in the Best Exotic Marigold Hotel films. So, how ironic it is that, when the story fast-forwards two decades, Pawar morphs into none other than Dev Patel, who starred in those movies. The actor does some of his most magnetic work yet as the adult Saroo, who's been adopted by John and Sue Brierley (David Wenham and Nicole Kidman), an unbelievably benevolent Australian couple. They give him a life beyond his wildest dreams. Not only does he attend college and study hotel management (honest!), he surfs. What could be less likely?

Here's what: Years of privilege riddle Saroo with guilt, and he eventually feels compelled to reconnect with his roots. He spends six years trying to retrace the route that brought him to Calcutta using Google Earth. It's product placement at its most poignant. The movie has its origin, in fact, in a promo for the program, which Brierley made in 2013 — you can see it on YouTube.

His story gets more magical by the minute in the final act. He even gets to date a character played by Rooney Mara. It would all be over the top if it weren't 100 percent true.

Luke Davies' screenplay is skillfully adapted from Brierley's 2014 international best seller A Long Way Home, so no spoiler alert is necessary. Brierley does finally find his way back to that village, and what happens next is guaranteed to get you where you live. It's a beautiful moment. Bring Kleenex.