The Ox-Head Incident is the twelveth episode of the third season of Jackie Chan Adventures.
The Chans and Tohru are on the hunt in the Himalayas for the noble animal containing the power of the ox talisman: super strength. They quickly locate it, only to find it's on the opposite side of the mountain. After several seconds, an avalanche occurs.
It's soon revealed that the avalance was caused by the yak containing the power of super strength, who ploughed his way through the mountain as it could smell the energy bar that Jade had just opened. However, before they can get the noble beast to safety, the Enforcers show up, who force Jackie, Uncle and Tohru to the edge of the ledge. Jade, however, is able to save them by causing a large rock to fall on and crush the Enforcers.
They end up back at the lair of Dark chi wizard Daolon Wong, who's tempted to destroy them when Hak Foo breaks in and almost immediately defeats Ratso, who's quickly followed by Chow and then Finn. Hak Foo advises Wong to give up his search for the Ox talisman, but Wong paralyses him and transforms him into another Dark Chi Warrior...
To protect the power of the Ox talisman, Uncle attempts to transfer the power from the yak to another vessel, though he does not say what that will be before he enters a trance. However, shortly after, Wong shows up with the recently-transformed Hak Foo, who is now capable of moves even more powerful than those when he was a mortal human. Jackie and Tohru was unable to effectively fight him off; Tohru even drops a rock on him, but it harmlessly just splits in 2 when it hits his head. Meanwhile, Wong realises Uncle is up to something and goes into a similar trance to attempt to foil his transfer spell. However, it soon becomes clear the transfer spell was completed, but Wong is able to trap Uncle's life force in a magic orb, and teleports himself and Hak Foo away.
Wong is eventually able to find out where the power of super strength lies from Uncle's life force, and sends Hak Foo to acquire it. Meanwhile, Tohru and Jade attempt to create another cow-bell that can locate the talisman power, with little success (they in advertently turn several monks in the monastery they travel to into guinea pigs), while Jackie infiltrates Wong's lair to steal back Uncle's life force. He succeeds in doing so, despite meeting resistance from Finn, Ratso and Chow. Tohru and Jade eventually succeed, and realise that the power of the ox now resides in Uncle's body. Hak Foo, however, steals it just as Jackie is returning with Uncle's life force.
Tohru next attempts to create a spell to release Uncle's life force, while Jackie goes after Hak Foo and Wong. Jackie attempts to persuade Hak Foo into turning against Wong, but he states that he likes how things are now, and attacks. Jackie dodges, and manages to foil Wong's spell (he throws a rock through the hole in one of Wong's hands). However, Hak Foo recovers and holds Jackie upside down over the cliff while Wong tries again, but is unable to complete the spell before Uncle's life force is released and travels back to his body. Upon waking up, he immediately smashes the ground that Wong is standing on, causing him to fall.
Hak Foo drops Jackie off the cliff as he prepares to fight Uncle, but fortunately Jackie manages to hang on a ledge below. Hak Foo is unable to hit Uncle though due to his supernatural strength, and eventually ends up being thrown off the cliff. Wong appears again, however, but is quickly dispatched by a spell cast by Tohru. They set off to transfer the power back to the ox and get it safely delivered to Section 13.
- This episode marks Hak Foo's first appearance in the third season. He is the only one of Wong's four warriors who feels completely comfortable and happy about his transformation, despite knowing full well that he is just a slave.