In Phnom Penh, Chou lives with her husband Khuon, their youngest son Sovanh, and the extended family, including Khuon's brother Meng, Chou's mother Mom and their grandmother, along with their other children Hout, Tuch, and Lili. In 1975, the Khmer Rouge topple the government and force the family to evacuate the city. On the brutal journey, Sovanh and his grandmother become separated from the group, and the guards forbid Chou from trying to locate them.
When they reach the neighboring town, they discover that their cousin Sok has become one of the revolutionaries and the entire town has been turned into a commune. The family is stripped of possessions and pressed into grueling labor with barely any food. Chou asks after her son and is assured he’s in a different labor camp but is forbidden to see him. Meng wants to leave, but Khuon insists they have no choice but to be subservient. At Chou's insistence, Khuon tries to cross the river to find Sovanh, but is captured and beaten. Tuch falls ill, and the family spends their last valuables to a woman from the camp, known for sleeping with the Khmer Rouge, in the hope of obtaining medicine. Tuch dies before help can return. The woman herself returns with her own son left in Chou's care, and Sok later takes pity on Khuon and allows him to try to find Sovanh, but by the time he arrives, the child has been moved again.
Throughout, Sovanh lives on with his grandma, and a girl he befriends at his work camp. Horrific deaths unfold around him, and the girl ultimately sacrifices herself to help Sovanh avoid capture while they steal food.
Meng makes a break for the border — Khuon runs after to wish him luck but is caught by a Khmer Rouge guard. Sok kills him, saving Khuon's life. Khuon and Chou return, but a vengeful Khmer Rouge kills Sok in retribution. The group is moved again on trains, and Chou is separated from the child she’d been trusted to watch. The train stops when one of the Khmer Rouge's daughters drowns in a well, and Khuon helps save her, angering Chou. Soon after, the men and women are driven to separate camps, leaving only Chou, her mother, and Lili. Months pass. The Khmer Rouge woman who would have drowned, Peuv, attempts to thank the group by sneaking food to Chou and her family, but Chou rejects it as a way to maintain dignity. Chou's mother notices that one of the guards fancies Lili and encourages her to use this to obtain food, but it is implied that the guard rapes her, and Lili hangs herself. Afterward, Hout returns from the men's camp, saying he was separated from Khuon; he finds the guard who harmed Lili and burns him alive in a thatched hut, but is killed, along with an innocent old woman accused of being a sympathizer. Chou's mother dies of starvation.
Years pass and an emaciated Khuon finds Chou in an infirmary. He tells her he’s found Sovanh, and she gathers the last of her strength to move on. The Cambodian-Vietnamese War begins, and as Vietnamese forces advance, the couple makes a final break for the Thailand border. Peuv covers for them, allowing their escape. After journeying far and wide, they finally locate a group of children, among them Sovanh, seemingly abandoned.
Reunited, the family makes one final push toward Thailand. Along the way, they encounter a mob of vigilantes who are about to kill Khmer Rouge members; Chou confronts them, tearing open her shirt to show she has suffered as they have and successfully saves Peuv. They are urged to follow them to Thailand, but she refuses, as she still has family in Cambodia. The trio reaches the border, and Khuon scouts ahead. As Chou and Sovanh watch, Khuon is spotted by Khmer Rouge guards; he deliberately runs away, allowing his family to slip past the border, and is shot. Sovanh and Chou, the last of their family, walk hand in hand through a field toward Thailand.
