At a 1936 Chicago, Illinois, street fight, mobster and promoter Dominici watches as his fighter loses to brawler Billy Kiss. Morgan, Billy’s manager, warns Dominici that his man does not have the skill to compete in the upcoming Battlecreek Brawl. In another part of town, Jerry Kwan practices acrobatics on the steel girders at a construction site while his girl friend, Nancy, watches. Soon after, gangsters demand protection money from Jerry’s father, Kwan, at his Chinese restaurant, and Jerry defeats the mob in an alley fight. Although Jerry overpowers the gangsters, Kwan would prefer that Jerry spent his time studying to be a doctor like his brother, Robert, instead of training in martial arts with his uncle, Herbert Kwan. Upon hearing that Jerry defeated his men, Dominici commands his nephew and associate, David Leggetti, to bring Jerry to him. At night, Jerry enters a contest at the roller rink to earn the cash prize and notices Leggetti conducting business with an opposing team member. In the first round, the skaters are sprayed with water from fire hoses and Jerry’s teammate, Jug, barely passes the baton to Nancy. After Jerry catches the baton from Nancy, two other skaters attack him. However, he outsmarts them and crosses the finish line victorious. Jerry and Nancy drive off clutching their trophy, while Jug decides to walk home and is beaten by Leggetti’s men. Jerry and Robert find Jug alive but unconscious, and take him to the hospital. Later, Jerry receives a mysterious phone call and is instructed to meet a contact, who will provide information about Jug’s attackers. Instead, Jerry arrives at a deserted outdoor theater and is attacked by the Woo brothers, a pair of martial artists. Dominici and John, an associate, sit down and watch the fight unfold. When Jerry wins, Dominici and John disappear. Back at the restaurant, Kwan voices his fears that Jerry will not be able to earn a living with his fighting. Although Kwan thinks Jerry can make money working at his restaurant, Jerry is unenthusiastic about joining the family business. Meanwhile, Robert asks Jerry to meet Mae Chan, his mail order bride from China, when her ship arrives at the dock in San Francisco, California. When Mae’s purse is snatched, Jerry retrieves it, and finds that Dominici’s men have kidnapped her. To ensure Mae’s safe return, Jerry agrees to be Dominici’s fighter at the Battlecreek Brawl in Texas for the $15,000 prize money. Since Robert has not yet met Mae, Dominici holds her hostage, while an imposter, Miss Wong, takes her place as Jerry trains for the fight. In Chicago, Jerry and Uncle Herbert hatch a plan to rescue Mae, breaking into Dominici’s compound and eliminating most of his men; however, they are caught, and although Dominici is impressed with their rescue attempt, he will not release Mae until Jerry wins the Battlecreek Brawl. In Texas, Jerry’s first opponent tries to run him down in a patrol car, but destroys a fire hydrant instead, ending the fight. Behind the scenes, Dominici’s rival, Morgan, has enlisted Leggetti’s help to eliminate Jerry from the competition. A stranger hands Jerry his uncle’s hat with a note warning that his uncle has been kidnapped. Jerry advances to the final against Billy Kiss, but is told that Herbert will not be harmed if he loses the fight. The brawl between Jerry and Billy commences, but before long Jerry disappears in the crowd. Although Herbert has been tied up and held captive, he escapes from Morgan’s men and climbs up the bell tower. Billy finds Jerry in the crowd and is about to finish him off when Herbert rings the bell and alerts his nephew that he is okay. Jerry is free to win the competition and attacks Billy repeatedly. When it looks like Jerry might win, Leggetti instructs Billy to take the fight inside a movie theater. There, Jerry is ambushed, but defeats the gangsters. In the street, Billy claims victory but Jerry reappears, and the fight resumes with the fighters using everything at their disposal. Jerry finally overpowers Billy with a series of acrobatic moves. Jerry is congratulated by the crowd and hoisted in the air, where he is joined by Nancy.