In a few days, Merlina, Rosa, and Nina will take exams at the school of magic. During a short break from studying, Merlina takes a walk by the Avalon lake, when she sees a fainted Odin. Guided by their courage, the three friends decide to help the fairies and find the magical potion that will save all the Odins. To succeed, they must dive into the depths of the lake, resist the spell of disorientation, face a whirlpool, and, above all, not forget to take their exams!