Terry Yue Siu-bo is a single father who single-handedly raises his two children, Natalie and Nicky, to young adulthood after his wife's death.

Siu-bo works as a traditional Chinese bonesetter and has kung fu skills, which he has passed on to his children, who display prowess while fighting each other in sibling disputes.

During this time, Uncle Chiu discovers Siu-bo's shop trashed and calls up Nicky to tell him of his father's disappearance.

Meanwhile, Siu-bo is injected with truth serum by Rocco's men, and in his degraded mental state, he reveals that he hid memory cards containing data about former spies in the lucky charms of his children.

After defeating the minions, a phone rings, and they get into direct contact with Rocco, who threatens their father's death if they do not help him in his quest for revenge.

Nicky and Natalie get back to Jason's house and find out that they require voice authentication from their father to access the file.

Nicky and Natalie try to leave to recover their father and find Uncle Chiu, but Jason traps them in his studio and reveals that he is Siu-bo's co-agent and does not want them to get hurt.

They fight their way through everyone, with Natalie breaking out Siu-bo and Nicky saving Uncle Chiu from a killing blow and defeating Rocco's son.