With his sister, a friend of hers and his mother, Billy Latreille - known as "Latrouille" because he is so afraid of everything - spends his holidays near Cap du Diable, in Bas-Saint-Laurent. He is scared when kayaking when he sees a beluga appear, and even more so when he meets Father Beaulieu, an old hermit and grumpy fisherman. A disturbing legend is associated with the cape of the Devil, which does not reassure Billy. Billy's sister and her friend on their side want to explore this beautiful place; they even plan to sleep there under the stars! A madness to which the mother agrees, provided that Billy accompanies them! How will the little one react? An opportunity is given to him to show new courage: indeed Billy saves a beluga from death by preventing Father Beaulieu from harpooning him.