Saroo (Dev Patel) lives with his sister, brother and mother. Although poor and hard, the family supports each other, and the days are still warm and full of joy. In an accident, Saroo and his brother were separated at the train station. By mistake, Saroo boarded a train bound for Kolkata, where Saroo became a street kid and was eventually sent to a shelter. Fortunately, Saroo was adopted by John (David Wenham) and Sue (Nicole Kidman) from Australia. Under the love of the two, Saroo grew up to be a promising young man. At school, Saroo met a girl named Lucy (Rooney Mara), and the two quickly came together. At a party, food from his hometown evoked Saroo's memories of the past, and he had the idea of returning to his hometown to find his family.