In the year 1431 in Thailand, Tien (
Tony Jaa) is held captive being beaten with
Kendo sticks. On the orders of Lord Rajasena (
Sarunyu Wongkrajang), his elbows and knees are snapped. As Lord Rajasena sleeps, Tien's guerilla fighters attempt to free Tien, but Bhuti Sangkha (
Dan Chupong) appears and kills them. Lord Rajasena offers to hire Bhuti, but he refuses and gives the offer to remove the curse which has been placed on Rajasena before leaving. Rajasena orders his men to kill Tien, but before this can be carried out, a man arrives with a message on paper indicating that he will take Tien's corpse, much to Rajasena's ire. The messenger returns Tien's body to the Kana Khone villagers. After fending off the village from invaders who after Tien's body, Master Bua (
Nirutti Sirijanya) feels guilty over Tien's imprisonment and becomes a
Buddhist monk. Pim (
Primrata Det-Udom) revives Tien to life, but finds that Tien is still crippled from his beatings. Tien then embarks on a rehabilitation regimen with the help of Master Bua.
Rajasena visits Bhuti at his temple to remove his curse, but Bhuti reveals his true motive of usurping Rajasena and becoming the new king. After a battle, Bhuti decapitates Rajasena his severed head curses Bhuti. After meditating, Tien returns to his village to find it in ruins, and the surviving villagers kidnapped and enslaved by Bhuti. Bhuti uses his magic to summon an eclipse. When Pim (
Primrata Det-Udom) reveals herself as Tien's companion, she is taken to Bhuti's palace where she is killed. Tien witnesses this killing from a statue and fights his way through the guards before confronting the Bhuti who launches a spear at Tien's chest. As he falls to his knees, defeated, he remembers Bua's words, and finds himself again atop the statue. Overcoming Bhuti's illusion, lightning strikes and Bhuti's eclipse magic is dispelled. Bhuti attempts to escape and is confronted by Tien. Bhuti attempts again to throw a spear at Tien, who catches and throws it aside. He then attacks Bhuti impaling him on an elephant tusk. Tien and Pim return to the village where they pray before the statue of the head of Ong Bak.