After leaving the zoo, Barbapapa finds refuge in the house that François' parents built for him. However, in the spring, a melancholic sadness takes hold of him. Worried, Jeanne and Edmond take him to Doctor Alcibiade who confirms that Barbapapa is in excellent health. Jeanne then has an idea: to regain his smile Barbapapa needs a Barbamama! But where to find her? Maybe on the moon?