Katie's mother, Mega Ninja, and Katie team up to defeat Wolfman and his army of robots. They succeed and Wolfman is locked away. But, Wolfman has a new plan in Book 5.
Katie discovers that Wolfman has escaped and plans to take over the world. With her ninja skills, she foils his bank robbery and captures him with the help of the police.
Tim and his sister Lilly get ready for Halloween. Lilly steals Tim's candy, but learns her lesson and apologizes. She is forgiven and becomes a better person.