In 1920s China, the nation is divided by infighting. Japan has become the most powerful force in Asia, taking over Northern Shanghai. With the city torn in half by international conflict, the popular nightclub "Casablanca" has become a hotbed of spies, mobsters, English officials and the Japanese military- all looking to gain control of the country, with little regard for what happens to its citizens.

Into this den of intrigue enters Chen Zhen (Donnie Yen), who has returned to China after fighting alongside the Allied forces in Europe, bringing some dark secrets from his past along with him. During the day, he's known as "Ku", and appears to be just another wealthy playboy. But at night, he takes to the street as a masked warrior, determined to subvert the Japanese invasion while becoming entangled with the sultry Kiki (Played by Shu Qi), who has a dangerous secret of her own. When his past catches up to him, Zhen is faced with near impossible odds- but his skills are formidable, and he's up to the challenge.

Combining the best of today's martial arts and superhero action with the classic spy thrillers of the past (and a healthy dollop of film noir on top), LEGEND OF THE FIST is the rare action film that truly gives the audience something they've never seen before.

The film opens with a lesser known history of the First World War: Chinese men on the Western Front. Between 1914 and 1918, France and Great Britain use their diplomatic influence to recruit soldiers from the Third World — China being one of them. Thousands of Chinese laborers are conscripted and transported to Europe to help the Allied war effort, most of whom end up dead in the line of fire. Chen Zhen is one of the few revered survivors who make it back to China in one piece.

Deprived of the wages they were promised, these Chinese soldiers develop a close bond akin to brotherhood in the field. When their bullets eventually run out, Chen Zhen employs his martial arts to conquer the battlefield, saving his compatriots' lives with his superheroic feat.

Chen Zhen is a fictional Chinese martial artist and culture hero created by Hong Kong writer Ni Kuang. The character first appeared in the 1972 martial arts film Fist of Fury, which starred Bruce Lee as Chen Zhen.

Since 1972, Chen Zhen has become the subject of numerous films and television series, including remakes and adaptations of the original film. Many well-known martial arts film actors have played the role of Chen Zhen before, including Bruce Lee and Jet Li.

Donnie Yen first played the character of Chen Zhen in a television series in 1995 that mesmerized audiences across Asia - including China, Taiwan, Singapore, and Japan. In legend of the Fist: The Return of Chen Zhen, Yen reprises this role in a completely brand-new take on the urban legend.

Chen Zhen's story varies in the different remakes and adaptations, but almost each story ultimately leads to his final quest to avenge Huo Yuanjia and shares a similar ending to Fist of Fury.

The character of Chen Zhen is believed to be based on Liu Zhensheng, a real student of Huo Yuanjia.