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.
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.