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

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.

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.

Humphrey the hamster and the students in Mrs. Brisbane's class get ready for the holidays and a special Winter Wonderland program.

Signs of spring are very exciting to everyone at Longfellow School. Mrs. Brisbane's class has seen flowers poking out of snow and baby birds hatching, and Just-Joey even brought in tadpoles that are growing into frogs.