On the outskirts of Herat, Mariam lives with her embittered mother, Nana, in a secluded hut. Born as a result of an extra-marital liaison between her mother and Jalil, a wealthy local businessman, the family lives outside the city in order to avoid confronting Jalil's three wives and ten legitimate children. Nana resents Jalil for his mistreatment of her and his deceptive attitude towards Mariam, whom he visits every Thursday. On her fifteenth birthday, Mariam asks her father to take her to see Pinocchio at a cinema he owns and to introduce her to her siblings. Jalil promises to do so but when he does not come to pick her up, Mariam travels to Herat herself, against the wishes of her mother. When she arrives at her father's home, she is informed he is away on a business trip. After spending the night on the street outside Jalil's home, Mariam discovers that Jalil had been home the entire time. Heartbroken, Mariam returns home to find that Nana has hanged herself. Mariam is temporarily moved into Jalil's house, to the displeasure of his wives. They pressure Jalil to remove Mariam from their household. Jalil arranges for Mariam to marry Rasheed, a widowed shoemaker from Kabul thirty years her senior, and move to Kabul. Rasheed is initially kind to Mariam, but over the course of seven miscarriages their relationship sours and he becomes increasingly abusive toward Mariam, angered by her inability to provide him a son.
Meanwhile, Mariam's young neighbor Laila grows up close to her father, an educated school teacher, but worries about her mother, who is deeply depressed following the death of her two sons fighting for the Mujahideen against the Soviets. Laila is close friends with Tariq, a local Pashtun boy with one leg, and a romance develops between them as they grow up. When Laila is fourteen, civil war breaks out in Afghanistan, and Kabul is bombarded by frequent rocket attacks. Tariq's family decide to leave the city and, while saying their good-byes, he and Laila have sex in a moment of passion. Shortly afterwards, Laila's family decide to also escape the city, but before they can, a rocket hits their home, killing Laila's parents and severely injuring Laila. Laila is taken in by Mariam and Rasheed, and as she recovers from her injuries, Rasheed begins courting her, to Mariam's dismay. One day, a man arrives at Rasheed's home to inform Laila that Tariq and his family died in a bomb blast on their way to Pakistan. Realizing that she is pregnant with Tariq's child, Laila agrees to marry Rasheed, convincing Rasheed that the child is his. Laila gives birth to a daughter, whom she names Aziza. Mariam initially treats Laila coldly, avoiding contact with her and Aziza. They eventually become friends, bonding over Rasheed's abuse of both of them after Aziza's birth. They form a close mother-daughter-like bond, enduring Rasheed's abuse and raising Aziza. One spring, Mariam and Laila attempt to escape from Rasheed, but are caught by the local police and returned to Rasheed. Rasheed beats them and nearly starves them to death.
The Taliban rise to power in Kabul and impose harsh rules on the local population, severely curtailing women's rights. Laila is forced to give birth to a son, Zalmai, via a Caesarian section without anaesthesia, as the local women's hospital has been stripped of its supplies. Laila and Mariam struggle with raising Zalmai, whom Rasheed dotes on and favours over Aziza. During a drought, Rasheed's workshop burns down, and he is forced to take other jobs, worsening his mood and the abuse. Due to a lack of food, Rasheed forces Laila to send Aziza to an orphanage and refuses to accompany her to visit Aziza. Laila endures beatings from the Taliban for travelling alone to visit Aziza.
One day, Tariq suddenly shows up on Laila's doorstep and reunites with Laila, much to her shock and joy. Tariq explains to Laila the events that led him back to Kabul. Laila realizes that Rasheed paid the man to lie to her about Tariq's death to convince her to marry him. Laila and Mariam agree to attempt to escape again, this time with Tariq's help. However, when Rasheed returns home from work, Zalmai informs Rasheed that Laila had a male visitor. Enraged, Rasheed begins a vicious beating and attempts to strangle Laila. To save Laila, Mariam kills Rasheed with a shovel. Stricken with guilt and knowing the authorities would be after them, Mariam decides to turn herself in to draw attention away from Laila and Tariq's escape with the children. Confessing the murder to the Taliban, Mariam is sentenced to public execution, and complies peacefully, glad that she has experienced true love and joy during the years she spent with Laila and the children.
Laila and Tariq successfully escape Afghanistan with the children and move to Murree, Pakistan, where they get married. After the fall of the Taliban, they decide to return to Kabul to be present for the rebuilding of Afghan society. They stop en route to Herat, where Laila visits the village where Mariam was raised. She meets with the son of a kindly mullah who taught Mariam, who gives her a box Jalil had entrusted to the family to give to Mariam, should she return to Herat. The box contains a videotape of Pinocchio, a sack of money, and a letter in which Jalil expresses his regret and love for Mariam, wishing he had fought for her and raised her as his legitimate child. The family return to Kabul and use the money to repair the orphanage Aziza had stayed in, and Laila works there as a teacher. She becomes pregnant with her third child, whom she intends to name Mariam if it is a girl.
