En 1959, Ip Man vit à Hong Kong avec sa femme et son deuxième fils. Vivant de ses cours de wing chun, il va se retrouver à protéger l'école de son fils d'un promoteur américain prêt à tout pour acheter le terrain. Il va alors voir apparaître un rival, Cheung Tin-chi, aussi doué en wing chun mais très pauvre.
The movie begins by Jackie Chan telling the story of the Old Summer Palace and its looting and destruction by British and French soldiers in the Second Opium War. Among the treasures stolen are twelve bronze heads of the animals of the Chinese zodiac.
In Shanghai during the 1930s, Sing and his friend Bone attempt to join the Deadly Axe Gang which ruthlessly control the city under leadership of Brother Sum. Sing seeks to restore his confidence after being humiliated as a young boy while trying to protect a mute girl from bullies, due to the failure of the Buddhist Palm method he had learned from a pamphlet he bought from beggar. Sing and Bone attempt to intimidate the residents of Pig Sty Alley but are chased off by its Landlady. Hearing of this, Sum orders Sing and Bone captured, while sending the Gang to reassert its authority from the humiliation. Three of the tenants, Coolie, Fairy, and Donut, are revealed as martial arts masters and defeat more than fifty of the Gang. Fearing retribution, the Landlady evicts the three, but they meet a pair of hired assassins using a magical guqin to launch invisible blades. Coolie is beheaded, and Fairy and Donut are mortally wounded before the Landlady and her husband the Landlord reveal that they too are martial arts masters, having gone into self-exile after the death of their son. The two defeat the assassins but Fairy and Donut die from their wounds. The Landlords temporarily evacuate the other tenants for their safety.
The Emperor's eunuchs have gained power and influence, the East Bureau and West Bureau spy and police the nation. They visit the shipyards, but only as a cover to execute those who would try and report their taking of bribes to the Emperor. Wandering hero Zhao Huai'an fights the leader of the East Bureau, defeating him and putting his head in a box and hanging it as a warning to other corrupt officials.
In AD 859, as the Tang Dynasty declines, a number of rebel groups are established, the largest of which is the House of Flying Daggers, based in Fengtian. Its members steal from the rich and give to the poor, gaining the support of the locals. Two police officers, Leo (Andy Lau) and Jin (Takeshi Kaneshiro), are ordered to kill the leader of the group within ten days.
Kit is a Hong Kong undercover cop who becomes a drug addict to infiltrate a crime syndicate which has been kidnapping people and sending them to Thailand, where the victims are killed and have their organs sold in the black market. The mastermind behind the syndicate, Mr Hung, has a rare heart condition and needs to undergo a heart transplant to prolong his life. Hung's younger brother is the ideal donor for a heart.
In Rome, Chen Ching-hua and her uncle Wang experience trouble with their restaurant from a mob boss who wants their property. When Chen refuses to sell, the mob boss sends gangsters to scare away customers. Appealing to an uncle in Hong Kong, Chen receives help in the form of Tang Lung, a martial artist. Disappointed, Chen asks how he can help her, but Tang confidently assures her that he is capable. At the restaurant, Tang learns that the staff have begun to learn karate, much to the annoyance of Quen, an employee who favors Chinese martial arts. Tang tells Quen that he should be open-minded and incorporate any moves that work. Before Tang can demonstrate his style to them, customers arrive, and the staff change clothes.
In year 689 of the Tang Dynasty, Wu Zetian is about to be crowned the first Empress in China despite opposition from Tang officials. To mark this occasion, she has a colossal Buddha figure built overlooking her palace. However, an official inspecting the Buddha's progress mysteriously erupts into flames. Penal officer Pei Donglai and his superior investigate and interrogates the supervising builder, a man named Shatuo, who was formerly imprisoned after he took part in a rebellion eight years ago. They find nothing, however, and Pei's superior dies soon after in the same manner as the official.
Chow Ti is a poor construction worker. He lives in a partially demolished house with his nine-year-old son, Dicky. Chow is eager to save money so he can continue sending his son to private school. However, Dicky is often bullied by other children and his teacher at school.
Tim est un ambitieux inspecteur-chef de la brigade des stupéfiants qui privilégie sa carrière avant tout. Chao plonge en tant que flic infiltré dans le circuit du trafic de drogue à Hong Kong et n’arrive plus à se reconnaître. Wai est le fidèle bras droit de Tim et cherche à gagner le respect des autres pour son travail. Ils sont tous les trois des amis de longue date qui risqueraient leur vie l’un pour l’autre. Mais leur nouvelle mission mettra leur sliens à rude épreuve.