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.
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.
Twelve-year-old Al Chaudhury discovers his late dad's time machine and travels back to 1984 with his pet hamster to prevent the go-kart accident that killed his father.