Lynne Jonell

When the Willows move into a new house, Celia, the youngest of four children, traps an enchanted hamster, who reluctantly agrees to grant the children one wish in exchange for his freedom.

A young boy really wants a snake of his own, and after his mother reads a book about snakes and takes him to a museum and a pet store to see some, he finds his own pet "snakes" around the house.