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.

Katie Carew wishes she could be anyone but herself, and turns into a hamster.

"When a fairy godmouse forces Whiskerella to wear glass slippers and attend balls night after night in search of a happily ever after, it's up to Princess Harriet Hamsterbone to break the spell and save the day"--

Humphrey, pet hamster at Longfellow School, learns that he has an important role to play in helping his classmates and teacher.