In San Francisco during the year 2000, Afghan-American writer Amir Qadiri and his wife, Soraya, observe children joyfully flying kites. Upon returning home, Amir receives a call from Rahim Khan, an old friend of his father's who is now in Peshawar, Pakistan.
The story takes us back to Kabul in 1978, where 10-year-old Amir, the son of a wealthy and philanthropic Pashtun known locally as Agha Sahib, whom he affectionately calls "Baba," shares a close bond with his best friend Hassan. Hassan, who is the son of Baba's devoted servant Ali, belongs to the Hazara ethnic group. Amir participates in the competitive sport of kite fighting, with Hassan acting as his spool-holder and skilled "kite runner," able to predict the trajectories of fallen kites and adept with his trusty slingshot. On Hassan's birthday, Amir surprises him with a special gift: a kite made in the United States.
During a kite-fighting contest, Amir breaks his father's record by claiming 14 "kills". However, their victory is marred when Hassan runs after the final defeated kite only to be confronted and cornered by Assef and his gang. Despite Hassan's courage and refusal to hand over the kite, the gang brutally assaults him. Amir watches this horrific act unfold in fear, paralyzed by his guilt and shame, leading him to distance himself from his loyal friend. When Baba and Ali inquire about Hassan's unusual behavior, Amir feigns ignorance. After a heart-wrenching moment, Amir confronts his father, asking if he would ever consider replacing Ali and Hassan, only to be met with indignation.
The trauma of that day overshadows Amir's enjoyment of his 11th birthday party. In a moment of spite, he frames Hassan for stealing his wristwatch, which Hassan accepts without protest. While Baba forgives Amir quickly, it leads to Ali feeling humiliated, prompting him to leave their employment, much to Baba's dismay.
As the Soviet Union invades Afghanistan in June 1979, Baba and Amir are forced to flee to Pakistan hidden in an oil tanker, leaving Rahim behind to look after their home.
Fast forward to 1988, Baba now owns a service station in Fremont, California, and runs a stall at a local flea market. Amir, having graduated from a community college, starts working alongside his father. One day, Baba introduces him to General Taheri, a former Afghan army officer. Amir’s eyes are drawn to Soraya, the general's daughter, leading him to share a story with her, only for the general to confiscate it.
As their lives progress, tragedy strikes when Baba is diagnosed with terminal lung cancer. Amir pleads with him to ask General Taheri for Soraya's hand in marriage, which he grants during a picturesque stroll. Soraya reveals her checkered past concerning a failed romance with a Pashtun man, but Amir reassures her of his unconditional love. They marry, shortly after which Baba passes away.
In 2000, Rahim persuades Amir to visit him in Pakistan to seek redemption. In Peshawar, a dying Rahim reveals to Amir that he had summoned Hassan back, and that Hassan had returned with his wife and son, Sohrab. After the Taliban seized power following a civil war, they demanded Hassan vacate his home, leading to his tragic execution along with his wife, while little Sohrab was sent to an orphanage.
With a heavy heart, Rahim implores Amir to return to Kabul and find Sohrab, delivering a letter written by Hassan, who had taught himself to read and write. Initially hesitant, Amir's world shatters when he learns that his father had an affair with Ali's wife, making him and Hassan half-brothers.
Disguised in a fake beard to adhere to Taliban restrictions, Amir searches for Sohrab at an orphanage, only to find that he has been sold to a Taliban official. An appointment is set, and to Amir's shock, Assef, once a bully, now assists the official. During a violent encounter, Assef introduces Sohrab as his "dance boy" and assaults Amir. In a display of bravery, Sohrab uses Hassan's old slingshot to shoot Assef in the eye, allowing him and a wounded Amir to escape to Peshawar, where they learn of Rahim's death, but also receive a letter meant for Amir.
As they settle back in San Francisco, Amir and Soraya welcome Sohrab into their family. Embracing their past and shared experiences, Amir teaches Sohrab the intricacies of kite flying and volunteers to be his "kite runner." In a poignant moment, as Amir chases a falling kite, he echoes a cherished phrase from his childhood: > "For you, a thousand times over."
