Ninjago High school hosts an annual work experience day for all the students, where each class is randomly assigned to do a job for work experience. Lloyd's class is chosen to be teachers at Hero School, and help the teachers there to teach various of subjects. However, while they do this, Romeo kidnaps Garmadon and plans on turning him evil again! Lloyd and his team and their powers aren't enough to stop him, and if they want to defeat Romeo and save Garmadon, they will need someone's help. Someone who knows this enemy better than them: The PJ Masks.