During the Second Sudanese Civil War, siblings Mamere (Arnold Oceng), Paul (Emmanuel Jal), Jeremiah (Ger Duany), Theo (Femi Oguns), Daniel and Abital (Kuoth Wiel) escape after their families and village are massacred. Theo is the eldest and is declared chief. After numerous days of walking in the wilderness & scavenging for food, they join a group of refugees but leave after they are caught by enemy soldiers and many people are killed. After sleeping in the grassland, Mamere wakes up and spots two enemy soldiers approaching them. Theo hides the rest of the siblings in the grass and lies to the soldiers that he is alone. He is taken in custody with the soldiers. The group eventually arrives at a Sudanese refugee camp in Nairobi, Kenya, where Daniel succumbs to disease and dies. Thirteen years later, among the thousands in the camp, the siblings win for relocation to the United States. Mamere is smart & is under training of the camp doctor.On arrival in New York City in Spring of 2001, Abital is unexpectedly told that she is to leave for Boston, where a family awaits. As their sister tearfully leaves, Jeremiah, Mamere and Paul board the flight to Kansas City, where they meet Carrie Davis (Reese Witherspoon), a brash employment counselor, who helps them find jobs, and Pamela (Sarah Baker), who provides them their house and support. Carrie was told to pick up the boys from the airport, when the regular liaison failed to meet them on time. The guys are taken aback by this brash, unmarried woman who claims that she provides for herself.Mamere tries to convince Pamela to help him regroup with her sister, but Pamela expresses her helplessness at doing so. Carrie is initially unable to get the guys any work as they have no work experience and zero social skills. But eventually Carries takes the help of her friends to teach the guys some social stuff and introduces them to the concept of lying. They find jobs. In Sep 2001, after the attacks in NYC, the refugee program is suspended indefinitely.Jeremiah works at a grocery store and teaches Sunday school at a local church, but later quits the job because he was caught giving old food to a homeless person rather than throwing it away. Paul works at a factory and makes friends with his co-workers, where he is exposed to drugs. Jeremiah has to meet Carrie again to help him fix another job interview. He tells her that their nickname for Carrie is Yardit, which means Great White Cow.Paul becomes increasingly erratic at work and one day is found by the police vandalizing property. Carrie & Mamere go to bail him out. When Mamere confronts Paul, Paul accuses Mamere of letting Theo be captured by soldiers. Had Theo not sacrificed his life, Memere would not have been alive. Paul rejects Mamere as his chief and pushes him away. The next day the boys make up. Carrie finally sees the rift in the family since Abital is not part of it. She agrees to become a host herself and convinces Pamela to approve of her as a viable host. She starts Abigail's transfer process from Boston.Mamere takes two jobs as a store clerk and a security guard to pay for schooling, as he aspires to become a medical doctor. On Christmas Eve, Carrie arrives at their home with Abital and the Lost Boys of Sudan celebrate their birthday on January 1, as they had never known the date when they were born.Abital receives an anonymous letter stating that someone entered the refugee camp in Kenya searching for the group. Thinking it is Theo, Mamere travels to Nairobi and searches the refugee camp after they tell him that Theo is not registered. After meeting James, an old friend, he is reunited with Theo the next day. Mamere tries to get immigration papers to multiple embassies and fails, but tells Theo that the "task" was done. At the airport, Mamere reveals to Theo that he could not get him a passport and instead gives Theo his own passport - a deception that is the 'good lie'. After a tearful farewell, Theo leaves and is embraced by his family upon arrival in the United States; Mamere remains in Kenya and works at the camp hospital.