What starts as a normal day at school for Power Pack quickly turns into a battle with their old foe, Carmody. Carmody's hatred of the Power kids has only increased in his absence; and he is now working as a mutant hunter with advanced personal flight and capture technology, under the alias of the Bogeyman.
In Julie's fifth grade classroom, a group of students is planning to cheat on the math test. Julie does not want to participate. In Alex's science class, he learns some physics that give him the idea to create wings for his costume. Katie is drawing in her kindergarten class - and her picture, as she explains, is of a "small, ugly" monster named Leech, who is holding a kitten. :)
Carmody corners Katie in her classroom and kidnaps her, telling her that he will kill her siblings if she resists. She manages to shoot off one power ball before she is placed in a bag. Alex sees the power ball from his classroom window, assumes Katie is in trouble, and assembles the rest of the team. Jack goes into Julie's classroom to tell her about the situation by shrinking to his smallest size and walking next to her desk; when Julie whispers back to him, the teacher overhears. Unfortunately, it happens at the same time another student is passing the test answers to Julie; the teacher arrives before she can discard them and she is sent to the principal's office for cheating.
The team tracks Katie and Carmody to the East River. They get him to drop the bag carrying Katie, and she falls into the river, near an ocean liner. Jack joins her in the water to encourage her to swim, and Alex and Julie rescue both of them before they are run down by the cruise ship. Carmody's flight mechanism is disabled, but he escapes.
The Power kids head back to school. Alex is made to do laps in gym class for cutting, Julie is sent to her appointment with the principal, Jack's teacher laughs, and Katie's teacher assumes that she has wet hair because she snuck off to play in the water fountain.