For a potion test, Flora has to find a rare and special flower that only grows in the Black-Mud Swamp. The Winx venture into the swamp together, where they meet some water fairies, victims of a spell cast by a red willow. The willow is capable of putting anyone who approaches it into a deep and long sleep. The five fairies battle a monstrous creature and the terrifying red willow. After a spectacular display of power, the fairies manage to get the flowers they need and defeat the red willow.