Harold and George's time-traveling Purple Potty lands them in an alternate universe where everything seems delightful, but evil lurks just beneath the surface, and leads to a battle between Captain Underpants and his own evil twin.

"Flippy, Molly, Li'l Petey, and twenty-one baby frogs each have something to say. Naomi and Melvin don't see eye to eye and Poppy perceives the world differently than her siblings. Will the baby frogs figure out how to work together and appreciate one another's point of view -- both inside and outside the classroom?"--Provided by publisher.

"Canine cop Dog Man is back, and he's about to be bested by the world's most conniving cat crook!"-- Dog Man, the newest hero from the creator of Captain Underpants, is still learning a few tricks of the trade. If only the Chief would throw him a bone every once and a while ... Dog Man needs to dry up the drool, dust away the dander, and roll out of the refuse if he's going to impress the Chief, and he needs to do it fast! Petey the cat is out of...

Piggy is back, and his newest plot is his most diabolical yet. Dog Man and the rest of your favorite characters must join together. What new villains are on the horizon? Where are they all coming from? And who will step forward to save the city when scoundrels sabotage our Supa Buddies?

When George and Harold hypnotize their principal into thinking that he is the superhero Captain Underpants, he leads them to the lair of the nefarious Dr. Diaper, where they must defeat his evil robot henchmen.

"The comic club is going in all different directions! Naomi, Melvin, and siblings are each trying to find their purpose. Naomi has an idea to get rich quick that causes a lot of commotion and emotion. And when faced with rejections, the friends try and try again to stay true to their vision. To top it off, a surprise visitor comes to class to stir things up. Will a desire for money and power cloud Naomi's purpose? Is it quitting time? Will the club...

"Dog Man is down on his luck, Petey confronts his not so purr-fect past, and Grampa is up to no good. The world is spinning out of control as new villains spill into town. Everything seems dark and full of despair. But hope is not lost. Can the incredible power of love save the day?"-- Provided by publisher.

The monstrous Turbo Toilet 2000 is determined to take revenge on George, Harold, and Captain Underpants.

A small mouse and his best friend, a giant flying robot, attempt to save the Earth when an evil Martian monkey and his mechanical creations attack.

Principal Krupp once again turns into the superhero Captain Underpants in order to save the world, and Jerome Horwitz Elementary School, from the evil talking toilets and the Turbo Toilet 2000.