Amir leaves Farid inside the Land Cruiser outside Baba's old home where Taliban officials now live--and where Sohrab is supposedly located. When the Taliban official emerges,
... wearing his dark John Lennon glasses, looking like some broad-shouldered, New Age mystic guru,
he orders one of his men to remove Amir's fake beard. After the two men exchange small talk, Sohrab finally appears--a dead ringer for his father, Hassan. Dressed like a court jester with heavy make-up, Sohrab dances for the men. When the official asks Amir "whatever happened to old Babalu," Amir reacts in horror: The official is Assef, the same boy who had sodomized Hassan on the day of the kite-flying tournament. Amir tells Assef that Sohrab is the boy he wants, and offers to pay for him. Assef orders the other Taliban out of the room and pulls out his old pair of brass knuckles: Amir can take Sohrab, but he must first defeat Assef.
Amir is beaten badly, and it appears that Assef will eventually kill him. But Amir feels happy: By taking the beating and the pain, he has finally found a way to absolve himself of his sins against Hassan. The beating is his way of receiving atonement.
My body was broken... but I felt healed. Healed at last.
Then, just as Hassan used to come to Amir's rescue when they were boys, Sohrab suddenly pulls out his own slingshot and inserts a brass ball into the cup. In one swift movement, he blinds Assef with the ball--fulfilling the promise that Hassan had once made himself to Assef. Sohrab helps Amir from the room, and they make their way to Farid's waiting Land Cruiser. Amidst machine gun fire, the three make their escape.