This is a 16 book collection. Summary: Offers four previously published adventures featuring Harold, George, and principal-turned-superhero Captain Underpants. (16 Books) 4 Captain Underpants and the Wrath of the Wicked Wedgie Woman. 4 Captain Underpants and the Big Bad Battle of the Bionic Booger Boy Part 1. 4 Captain Underpants and the Big Bad Battle of the Bionic Booger Boy Part 2. 4 Captain Underpant and the Preposterous Plight of the Purple Potty People. Epic Novels Fifth, Sixth, Seventh, and Eighth.