In 1964, following the death of his wife, Ip Man (Donnie Yen) (an unassuming Chinese Wing Chun master originally from Foshan) discovers he has throat cancer due to smoking. After his rebellious son Ip Ching (Jim Liu) fights back against a bully and is expelled, Ip decides to travel to San Francisco upon the invitation of his former student Bruce Lee & to look for a new school for his son at the same time. His student, Bruce Lee (Danny Chan), has upset the local martial arts community in San Francisco by opening a Wing Chun school, teaching the Americans martial arts and writing an English language book on martial arts. He discovers from an associate and his friend, Liang Gen (Ngo Ka-Nin), that a referral letter from the Chinese Consolidated Benevolent Association is needed to enroll into a school. Wan (Wu Yue) (Master of Tai Chi), the president of the Association, refuses to write the letter as Ip does not agree with the grand-masters' opinions on Bruce Lee's actions (Wan wants Bruce to stop accepting non-Chinese students into his Dojo and also to withdraw his English book on martial arts from publication). After a brief fight with Wan where they test each other's Kung Fu, he leaves.While leaving the school after a meeting with the principal, he chances upon the daughter of Wan, Yonah (Vanda Margraf), being bullied by a rival cheerleader, Becky (Grace Englert), and her friends. Ip saves her and escorts her home, with Becky accidentally cutting herself with a pair of scissors. Wan accuses Ip of using his daughter to get the letter and challenges him to a fight for it. The fight is disrupted by an earthquake, and Wan tells Ip they will finish their fight at the upcoming Mid Autumn Festival. Ip refuses, explaining that he merely escorted his daughter home for her safety and leaves.Becky complains to her parents that she had been bullied. Her father Andrew Walters (Andrew Lane), who is an officer of the Immigration and Naturalization Service, is pressured into holding the Association responsible and deporting all Chinese associated with them. Meanwhile, Hartman (Vanness Wu), a Staff Sergeant in the United States Marines, attempts to convince Barton Geddes (Scott Adkins), the Gunnery Sergeant, to incorporate Chinese martial arts into their hand-to-hand combat training. Geddes proves that the Marines' current Karate training is superior by asking him to fight the Marines' Karate instructor, Colin Frater (Chris Collins), who defeats Hartman. Hartman later manages to convince the Commanding Officer about doing so and is instructed to film the Mid Autumn Festival happening at the Association for research, which upsets Geddes.Geddes asks Frater to challenge the grand-masters at the Festival, defeating a few of them until Ip interferes and defeats him badly. Meanwhile, Wan, who was supposed to be present at the festival, is arrested by the immigration officers. Upon seeing Frater defeated, Geddes barges into the Association to find out where Wan is kept and defeats everyone there. He finds that Wan is in custody of the INS. He then threatens Walters to release Wan into the Marines' custody before bringing Wan into the camp to fight him. Due to a tip-off by a student of Lee, the Association is left empty by the time the immigration officers raid the place. Lee provides refuge for the Association, earning their respect.Wan is seriously injured from the fight with Geddes. Ip, filled with emotions, finally reveals to his son that he has cancer, which finally allows him to talk to his father over the phone after many attempts by Ip. Ip is brought into the Marines' camp by Hartman, and defeats Geddes in a fight. Wan has already prepared the letter for Ip, but the latter said that he does not intend to move to San Francisco as he does not like the place. Ip reconciles with his son. A strong but weary Ip instructs his son to film him as he demonstrates Wing Chun on the wooden dummy. Until in 1972, Ip succumbs to his cancer at age 79, Lee pays respect to his master at the funeral and it is revealed in the epilogue that the Marines had officially incorporated Chinese martial arts into their routine in 2001.