After finding and adopting a child, a man gets a job at an all-girls school which doesn't allow families. Once the girls find the baby, they become his forty little mothers. At the same time, the child's true mother searches for him.

Prosper, engagé comme professeur dans un pensionnat de jeunes filles, trouve un bébé devant sa porte. Il est contraint de le cacher dans sa chambre, mais son secret est vite éventé, et il est menacé de renvoi.