Relates the tangled events that lead the students of the Unexpected School on Hurricane Peak to foil the wicked Sir Quincey and his accomplices and to solve several mysteries.

Every school has its secrets, but in Ms. Snickle's classroom the secrets are extraordinary, and when Lacey sets out to learn and tell them all, she puts Ms. Snickle's job in jeopardy.

The eighth grade's plan to get two reluctant "lovers" together by means of a classroom production of Shakespeare's play has some very unexpected results.

When Stink discovers that Pluto has been downgraded from a planet to a dwarf planet, he launches a campaign in his classroom to restore its status to that of a full-fledged member of the solar system.

Tired of following the strict rules of their grumpy replacement principal, second grader A.J. and his classmates try to find a way to bring back eccentric but lovable Principal Klutz, who was fired for bringing a wild turkey to the school's Thanksgiving Day assembly.

Fly Guy visits the school cafeteria and gets the lunch lady fired.

Captain Underpants and his friends, having dispatched Melvin Sneedley, the Bionic Booger Boy, must join the fray again when they realize they have forgotten about Sneedley's sidekicks, the Robo-Boogers.

Having earned a scholarship to a private girls' high school, self-proclaimed psychic investigator Gilda Joyce investigates the circumstances surrounding the drowning death of a student whose ghost supposedly haunts the campus.