A child, Luk Siu-fung, finds an injured dog lying on the railway track, about to be killed by a passing train. She rescues the dog and takes it home, naming it Prosperous. Child and dog become fast friends. Lau Fei-lung, a drifter, takes shelter from the rain at Siu-fung's home and is offered a place to stay by Siu-fung sister Yuk-wah and grandma. Squire Choi Pao's sons, Tai-fu and Yee-fu often bully Yuk-wah. Lau teaches these bullies a good lesson and Yuk-wah is greatly impressed. Squire Choi is angry that his sons were beaten and asks gangster Lui Hak-fung for help. (HKFA)