The imaginary antics of a hamster with a humongous appetite who grows to enormous size.

On Groundhog Day, the students in Mrs. Connor's class try to find out whether the class hamster can predict the weather as well as a groundhog.

Guinea pig Sasspants knows something is wrong with ninth-grader Viola, the new pet shop assistant, so when Mr. Venezi goes missing Sasspants and Hamisher put their private investigation skills to the test.

"Matt Hunter is expecting the latest sword-and-fantasy video game, but he's in for a disappointment when he receives a hamster for Christmas instead. A hamster called Snuffles. A hamster that dies, but somehow keeps going. A zombie hamster that has his eye on Matt"--

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

When guinea pig Sasspants leaves Mr. Venezi's pet shop to live with Detective Nichols, and hamster-detective Hamisher retires, the case of the missing bookstore cat must be solved without their help.