Bino wants to obtain the power of Claire de Lune, a mysterious flying creature.

A young man, Jean Liber (Paul Guèvremont), who, at the end of his cours classique, decides to leave his rich, happy family and his finance, Pauline (Denise Pelletier), in order to become a missionary in China. This story of his struggle, 'at the crossroads' between love and God's calling, is clearly a pretext for a film designed to encourage young men to enter missionary work.