When the Willows move into a new house, Celia, the youngest of four children, traps an enchanted hamster, who reluctantly agrees to grant the children one wish in exchange for his freedom.

Humphrey the classroom hamster has adventures going to the library, learning about the ocean, and sailing across a pond on a sailboat.

While continuing to help his classmates solve their problems, Humphrey, pet hamster of Longfellow School's Room 26, faces many surprises, like rolling in a hamster ball, a substitute janitor who might be an alien, and the possibility of Mrs. Brisbane retiring.

When Principal Decker closes Boerring Elementary School's library due to severe budget cuts, Einstein and his friends in Ms. Moreno's class try to reopen it by planning fundraisers, including shooting a video that stars Einstein and Marlon the turtle.

"Eleven-year old Sam befriends a hungry class hamster that undergoes a freaky transformation"--

When Ms. Moreno's class appears on the hit game show Kids Know Stuff, the show's host walks off the set but with the assistance of a sound engineer, Ned and Marlon help Einstein get ready to host the show and save the day--if only he did not have stage fright.

When Humphrey the hamster returns to Mrs. Brisbane's class after the winter break, a new class pet and some other surprises give him an opportunity to reflect on the meaning of friendship.

Stanley the hamster is building a home for Myrtle the mouse, but he needs the help of his friend Charlie to make sure it comes out just right.

Twelve-year-old Al Chaudhury discovers his late dad's time machine and travels back to 1984 with his pet hamster to prevent the go-kart accident that killed his father.