Missy already defeated her former best friend, the supervillain Melvira, in an epic showdown, so how hard can making friends at middle school be? Well... Bootcamp Leader Gru is the new school principal, and she's ready to kick Missy out at the first sign of trouble. Then Melvira enrolls at Missy's school, and she's being much too nice. Melvira wants to run for student body president, and Missy doesn't trust her. Missy starts to seem like the paranoid one for thinking Melvira's up to something evil again. But when a cursed bunny head begins to turn their town into zombies, the two may have to team up once more to fight the greater evil, and discover if they can still be true sisters-in-trouble.