In 1986, Saroo, a five-year-old boy, lives with his elder brother Guddu, his mother and his younger baby sister in Khandwa, India. Guddu and Saroo steal coal from freight trains to trade for milk and food. One day, Saroo follows his brother to a job and they arrive at a nearby train station, where Saroo decides to stay back and take a nap. Guddu tries to wake him up, but Saroo is too tired. When Guddu does not return, Saroo searches for him and boards a train presuming Guddu is aboard. He falls asleep again in one of the compartments, and wakes up to find the train in motion. After several days, it arrives in faraway Calcutta, where he does not understand the local Bengali language. He stands at a ticket counter and tries to obtain a ticket home, but the attendant does not recognise the name of his village, which Saroo says is “Ganestalay”. He spends the night in the station with some streetchildren, but is then woken up and forced to run when a group of men try to kidnap them.

Saroo continues to wander around the city before coming across Noor, a seemingly friendly woman who takes him back to her apartment. She tells Saroo that a man named Rama will help him find his way home. Saroo runs away, sensing that Noor and Rama have sinister intentions, and escapes Noor when she chases after him. After two months of living near the Howrah Bridge, Saroo is taken to the police by a young man. Unable to trace his family, they put him in an orphanage. Three months later, Saroo is introduced to Mrs. Sood, who tells him she has placed an advertisement about him in several local newspapers, but no one has responded. She then tells him that an Australian couple is interested in adopting him. She begins to teach Saroo basic English and he moves to Hobart, Tasmania in 1987, under the care of Sue and John Brierley, where he slowly starts to settle in with them. A year later, they adopt another boy, Mantosh, who has trouble adjusting to his new home and suffers from rage and self-harm.

Saroo returns to his hometown, and with the help of a local English speaker, has an emotional reunion with his biological mother and sister. He also learns that Guddu is dead. Saroo’s mother never gave up hope and believed that one day her missing son would return, and never moved away from the village. The film ends with captions about the real Saroo’s return to India in February 2012, including the fact his brother Guddu was killed by a train the same night that they were separated as children. Photos of the real Australian family are shown, as well as footage of Saroo introducing Sue to his biological mother in India, who deeply appreciates Sue’s care for her son. Saroo later learned that he had been mispronouncing his own name, which was actually Sheru, meaning “lion”.

In October 2014, Dev Patel and Nicole Kidman were cast in the film for the lead roles, although they were nominated in supporting categories. In January 2015, Nawazuddin Siddiqui, Priyanka Bose, Tannishtha Chatterjee, and Deepti Naval joined the cast. In April 2015, Rooney Mara, David Wenham, and Divian Ladwa also joined the cast. Pallavi Sharda also joined the film’s cast to play Saroo’s friend. Hauschka and Dustin O’Halloran composed the film’s score.

Principal photography on the film began in January 2015 in Kolkata, India. In mid-April, filming moved to Australia, in Melbourne and then to several locations in Tasmania, including Hobart. Kidman filmed her scenes in Australia.

The film had its world premiere at the Toronto International Film Festival on 10 September 2016. It served as the opening night film at the Zurich Film Festival on 22 September 2016. It also screened at the London Film Festival on 12 October 2016, and at the Hamptons International Film Festival on 7 and 8 October 2016. The film was released in the United States on 25 November 2016, in Australia on 19 January 2017, and in the United Kingdom on 20 January 2017.

Lion was made available on Digital HD on 28 March 2017, and was then followed by a release on Blu-ray and DVD on 11 April 2017. The film debuted at No. 10 on the Top 20 NPD VideoScan chart.