Planet Harmonie is populated by creatures with forms unknown to humans. Despite the diversity of bodies, their speech consists solely of two words, yes and no. This is what Jésus Pérez discovers upon landing his spacecraft there, his hands full of gifts, manifesting a desire for peace and cultural sharing. During his quest, in search of the master of the land, he will have to face the hostility of the inhabitants, whose cause he does not understand despite numerous attempts at communication. Invaded by profound discouragement, he even begins to question his mission.