A young boy named Saroo lives with his impoverished but loving family in a rural village in India. One night, he accompanies his older brother Guddu on a work trip, but they get separated, and Saroo accidentally boards a decommissioned passenger train that takes him over a thousand miles away to Calcutta. Lost and unable to speak the local dialect, he faces numerous challenges and dangers while surviving as a street child. Eventually, Saroo is placed in an orphanage from which he is adopted by an Australian couple, Sue and John Brierley, who raise him in Hobart, Tasmania.

Years later, as an adult studying hotel management, Saroo begins to experience flashbacks of his old life in India. With the encouragement of his friends and girlfriend, he embarks on a quest to find his lost family using the evolving technology of Google Earth. This journey of self-discovery brings emotional challenges as he balances the love he has for his adoptive parents with his yearning to reconnect with his origins. Saroo’s determination to piece together fragmented memories and locate the place he once called home ultimately leads him on an extraordinary path filled with both hope and heartache.