In the forties in Japan, a group of brilliantly qualified university students are selected to break all ties with their previous lives and form the Japanese spy service.

lchiro, the president of Mihara and Co., is henpecked by his wife Momoko, a clever and beautiful woman, but prattling and intrusive. She makes her younger sister Nashiko marry lchiro's younger brother, Jiro, manager of his company and now plans to marry her youngest sister Kyoko to her husband's youngest brother, Saburo. This means her domination of the Miharas and their business, a fine triple play which would gain her the title of "The Most Valuable Madam." However, in opposition to Momoko, Kyoko boldly declares that she will never marry Saburo. However Saburo is a most attractive young man and attracts Kyoko. Will she or her elder sister be able to win the title of "The Most Valuable Madam"?