Due to the hijacking of gangsters, a pair of twin brothers were separated at birth. The younger brother Wan Ming (Jackie Chan) was picked up and raised by a dancer. He wandered around the bottom of society all day long. In order to help his friend pick up girls, he met the singer Barbara (Maggie Cheung), which offended the underworld; the older brother Ma You (Jackie Chan) was taken to the United States by a wealthy couple, received a good education and grew up to be a famous musician. When he returned to Hong Kong to hold a concert, he met the daughter of his uncle, Tang Xin (Li Zhi). By chance, the two exchanged roles and entered each other's lives. Because everyone couldn't tell who was Ma You and who was Wan Ming, jokes kept coming out, and Barbara and Tang Xin's minds gradually changed. At the concert, Wan Ming waved his fingers randomly and didn't want to be a big success. Under the coercion of the gang, Ma You drove to save Wan Ming's friend Tai Shan who was held hostage by the gang. Then, the two brothers began to join hands to fight the powerful enemy.