Miss Horrid is the meanest teacher at Plonkton Primary. From forcing her class to measure blades of grass in science class to imposing a Birthday Dirty Dishes Duty, she could even be the meanest teacher in the whole world! When Miss Horrid cancels the class excursion to the Fun Park and replaces it with a School History Tour, ten-year-old Hazel decides enough is enough. Together with her best friend Aki and her next-door neighbour, Stella the Robotics Champion, Hazel designs Robo-Teacher, an AI-powered robot, to replace mean Miss Horrid. It’s not long before Robo-Teacher turns robo-evil, controlling traffic lights across the city, making satellites fall from the sky and trying to demolish the town to make way for a gigantic robot-building factory. Can Hazel save her school from being destroyed by an evil robotic teacher, which she helped create?