The only son (Tony Leung Ka Fai) in a family of police officers marries Mina, an ambitious `half-breed' colleague (played by Joyce Godenzi), incurring the resentment of his four sisters, all policewomen, especially the eldest, Ling (Carina Lau). There is pressure on Tony to father a son, to keep the male line going, although Mina wants to delay pregnancy until she gets promoted to Superintendent.