After the events of the previous film, Tien is captured by the evil Rajasena and, despite his fiery resistance, tortured into utter ruin. Only the intervention of the Ayutthaya Kingdom saves Tien, taking him to the village where he passed his childhood, but by then the young warrior is already turned into a cripple unable to stand on his own feet. At the same time, a new, supernatural enemy is rising.
In his new state, Tien will have to learn to rebuild his life and give a new meaning to all he knew, helped by the enlightenment of Buddhism and the beauty of Thai dance, and hopefully to stop the kingdom of terror involuntarily brought by Rajasena's ambition.
The last film of the trilogy and the intended climax of the previous film. After its grueling production, not unlike his character, Jaa decided to become a Buddhist monk for real and retire temporally from filmmaking.
The film contain examples of the following tropes:
- All There in the Manual: Bhuti Sangkha's complete name is never said on screen. Rajasena only calls him a "crow" (not without reason, as "Bhuti Sangkha" literally means "Ghost Crow").
- Ambiguous Situation: The lightning that strikes Bhuti and depowers him before the climactic fight. A side effect of his powers stopping working? Tien's work through his own spiritual powers? A sign that the gods, whom Bhuti previously taunted, are acting against him? All at once?
- Artistic License – Physics: Apparently, having an elephant pulling a gigantic stone structure with a rope is enough for the structure somehow being launched high into the air over the elephant and land several meters in front of him. Justified because all of this is happening just in Tien's mind.
- Back for the Dead:
- Five of the previous film's Pha Beek Khrut bandits (the Chinese, the wrestler, the samurai, the guy with the iron rings, and the guy with the twin sabers) return to try to rescue Tien, but they are all killed by Bhuti.
- The samurai of the wicker basket and a bunch of the masked assassins return as well, but all of them die in a mutual kill against the Ayutthaya guards.
- Bad People Abuse Animals: We see what an utter bastard Bhuti is when he starts killing elephants and drinking their blood.
- Barefoot Sage: Master Bua ditches his sandals when he becomes a Buddhist monk, and a sign of Tien's newfound spirituality is that he does the same.
- Battle in the Center of the Mind: The whole climax, a battle in which the returning Tien submits to the rage of watching Pim die, beats down a lot of guards, and dies to Bhuti's spear, turns out to be just a mental vision of what will happen if he gives in to unskilled emotions. In the real battle, knowing his own rage is fueling Bhuti's power, Tien depowers him by gathering his inner peace, humiliates him in hand-to-hand, and ultimately defeats him.
- Big Bad: Rajasena. Then Bhuti.
- Characterization Marches On: In the previous film, Bhuti was a silent, stone-faced enforcer that didn't really stand out in Rajasena's assassins squad, of which the masked samurai seemed to be the leader. In this film, it turns out he is an evil mystic, seemingly unrelated to the other henchmen and evidently of a higher rank in Rajasena's payroll, and is quite talkative, expressive and twisted. Speaking of the samurai, he has lines in this film, while in the previous he was also voiceless.
- Churchgoing Villain: Although evil, Bhuti is spiritual on his own right. Not easy to spot, but when he becomes king, it can be seen he has moved his tantric deity statue from his cave to his new palace. He might laugh at others' deities, but he keeps worshipping his even after having achieved what he believes to be absolute power.
- Contrived Coincidence: The Ayutthaya messenger brings Tien to a village to be healed, apparently without knowing it's the same village where he passed his early teenage years.
- Crucified Hero Shot: Tien gets one while tied in Rajasena's palace.
- Cryptic Background Reference: A flashback shows Rajasena poisoned a former higher up of his with Bhuti's help. It's never revealed know how does this exactly connect with his established background in the duology (the previous film is apparently not subjected to any Continuity Drift - this film shows Rajasena still answers to the Ayutthaya king and his Garuda statue is intact).
- Dented Iron: Tien's body is damaged by torture. When he recovers, he can hardly stand on his own feet.
- Diabolus ex Machina: We are never told who or what is Bhuti, only being shown that he is some kind of evil supernatural warrior.
- Driven to Suicide: Finding himself in a crippled state, Tien drags to a cliff intending to jump off, but he is stopped by Mhen and Master Bua.
- Dual Wielding: The Ayutthaya messenger and his guards carry all two sabers on their backs.
- Enlightened Antagonist: Bhuti seems to be some kind of ascetic, as he sports sutras in his skin, has a murti and some tantric paraphernalia in his cave, and even appears presiding a spiritual ceremony in Rajasena's flashback. This implies his powers are the result of spiritual practice and therefore not evil themselves, with only his twisted, egotistical usage of them being evil (something possible in Hindu and Buddhist mythology, where demons can gain power by ascetism and god-worship themselves, and even enlightened people can fall and become evil).
- Enlightenment Superpowers:
- Bhuti can summon eclipses with the powers achieved through his spiritual practices. It's likely they are just illusions, though.
- Tien's fighting style after coming back from his crippling is notably more unrealistic and improbable than his previous martial arts, instead resembling tai chi or kung fu choreographies, with a lot of artistic stances, superhuman blocks and improbable hand throws. This implies his newfound spirituality has granted him a much higher power than his brutish, earthly martial arts ever did.
- Evil Is Not a Toy: Rajasena soon discovers that becoming involved with an evil wizard is not a safe activity.
- Face Death with Dignity: For all his wickedness and decreasing sanity, Rajasena ultimately goes down fighting and spends his (supernatural) last seconds cursing Bhuti.
- Foil:
- Bhuti's attempt to contaminate Bua with darkness fails due to the old master's meditative ability, which allows him to remain serene and expel the darkness. Bhuti later tries it on Rajasena, and this time it works wonders because, unlike Bua, Rajasena is a greedy, unskilled man without any control over his emotions.
- At the end of the film, Tien and Bhuti are specular images: both of them have gained spiritual power, but while Bhuti only acts on his own benefit, Tien has tamed ego and acts on favor of his people.
- Gaia's Vengeance: In a possible reference to the Buddhist concept of maravijaya, which is in fact the attitude the Ong Bak statue shows, Tien invokes this in the climax, when he defeats Bhuti not by beating him up, but by throwing him to the mercy of the elephants Bhuti had been taming to kill.
- Hard-Work Montage: Several during Tien's rehabilitation. First, he isolates himself to a temple to meditate and perform physical therapy to re-learn to walk on his own. Second, Pim teaches him the traditional khon dance to help him re-coordinate his limbs. And finally, he creates a new martial combining Muay Thai and dance to recover both his mind and body. He spends enough time meditating and practicing that he grows a beard and his body shows visible ribs.
- Hijacked by Jesus: At the end of the movie, intentionally on the producers' part or not, Tien ends up doing a full Moses impersonation: in long robes, barefoot and with a staff, returning to the place where his people were enslaved to build palaces and temples, in order to challenge their evil overlord and free them. In a film full of Hindu and Buddhist background, this sticks out like a sore thumb.
- Human Sacrifice: The presence of skulls in Bhuti's cave implies he sacrifices people. However, they might also be bones exhumated for ritual purposes, as dharmic esotericism contemplates both things in its most hardcore variations.
- Inspirationally Disadvantaged: Mhen, the village madman, who also doubles as Comic Relief. Most of what he says is nonsense, but it's surely hard to disagree with him when he points out that laughing is better than crying. More decisively, his shenanigans end up distracting a suicidal Tien enough time for Master Bua to reach him.
- Logical Weakness: Bhuti's powers are fueled by his enemies's negative emotions, like fear and rage. Therefore, when Tien lets his rage go and achieves a higher state of mind while confronting him, the villain finds himself literally powerless.
- Martial Arts Staff: Subverted. In a sort of Take Up My Sword moment, Master Bua hands Tien his danda before he goes to confront Bhuti, but the item is ceremonously discarded before the battle and therefore not used.
- Mind Screw: The final battle can be somewhat confusing by the moment it's revealed to be all in Tien's head.
- Noble Demon: The guard captain oddly abstains from killing the annoying Mhen on the spot, even althogh the crazy had been vexing him and even repeatedly punching him in the face (It Makes Sense in Context). The guard either doesn't consider Mhen a target or doesn't want to make an obvious madman responsible for his actions, both of which are quite delicate for a villain.
- Off with His Head!: Rajasena receives this treatment, and for some reason, presumably related to the curse, his severed head keeps talking after being cut.
- Old Master: Bua, who becomes a Buddhist monk in order to level up in wisdom.
- One-Man Army:
- Tien, as always, fights his way through many soldiers.
- Bhuti when he curbstomps Tien's fellow mercenaries and Rajasena's soldiers.
- The Plague: There seems to be one in the countryland as a consequence of Bhuti's powers.
- Shout-Out: The film makes a Whole-Plot Reference to Kung Fu Hustle, only in medieval Thailand and without most of the comedy. Even in the visual field, Mhen's hairdo reproduces exactly the Beggar's, and Tien's natayuth fight scenes lift entire moves from Sing's fight against the Axe Gang, such as the double reverse forearm KO and the pull-in shoulder block.
- Stone Wall: With his new fighting style, Tien engages Bhuti in peaceful, defensive fashion, using endless dodges and blocks and only attacking with humiliating throws and soft strikes. At the end, he defeats Bhuti not by scoring some technique, but by simply lifting him up with his hand and dropping him on a furious elephant.
- Redemption Equals Death: As shown in the flashback, Tien's adopted father Chernang, who killed his real father, allowed himself to be killed by Tien both to atone for killing his father and to ensure that the rest of his own family is kept safe.
- Wins by Doing Absolutely Nothing: Tien manhandles Bhuti by using a defensive and relaxed martial style, barely attacking at all during minutes of fighting. Even when he finally goes to finish him off, it's not by Tien's hand, but by a furious elephant's tusk.
- Wizard Duel: In a sort of duel of asceticism, Bhuti sends darkness to infect Master Bua, but the latter calmly expels the darkness out of his body through pranayama. Still, Bua decides it not to be enough and realizes he must become a monk.
