"To Humphrey and the students at Longfellow School, spring seems impossibly late this year. Fortunately, planning a school Family Fun Night keeps the students (and classroom pets) busy as they look for signs of the changing seasons"--

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

When summer arrives, Humphrey, the pet hamster of Longfellow School's Room 26, is surprised and pleased to learn that he will be going to Camp Happy Hollow.

After the holidays, Humphrey is shocked by a big surprise in Room 26-a new class pet! Humphrey tries to be welcoming, but Og the frog doesn't respond to any of his friendly squeaks or visits (remember, he has a lock-that-doesn't-lock). Plus, the students are so interested in Og, they almost stop paying attention to Humphrey altogether. Humphrey doesn't like the mad-bad-sad feelings he's had since Og came, but luckily he still gets to have adventures...

Humphrey, the pet hamster of Longfellow School's Room 26, learns that his classroom is full of secrets, the most important of which is that a student will be leaving soon.

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.

"Harriet Hamsterbone sets out to reverse the curse on twelve mice princesses who are forced to dance all night, every night"--

Humphrey the hamster is puzzled when unfamiliar students fill Mrs. Brisbane's classroom at summer's end, but he soon learns that his friends from last year are fine and that the new class needs his special help.

Little mouse cannot sleep because it is too quiet, but when he really listens he finds the night is full of all sorts of sounds--so many, in fact, that it is too noisy to sleep--