One terrible day, a strange insect with the body of a bee and the wings of a bat stings Grandpa John, who falls desperately ill. Grandma Rini enlists the help of her witch sister Magda. With Magda's help, Thomas and Julia find out that the insect is a magical creature. To cure Grandpa John, special ingredients for a magic potion are needed. When they go to the mystical forest to gather them, they run into a fearsome enemy determined to stop them. Their grandfather's life is hanging by a thread, and time is running out. Can Thomas and Julia save his life?