Alan is a twelve-year-old orphan who has determined never again to trust an adult. The authorities who took care of him until his Great-aunt Jessie could bring him to live with her had also taken his pets off to be "well cared for." That turned out to mean "put to sleep." Alan has rebuilt his animal kingdom while living with Aunt Jessie. She's not exactly wild about animals, but she understands Alan's love for them. Every-thing seems to be going well for him and the kingdom (a dog, a cat, a rat, a hamster, and a pair of gerbils) until one tragic day Aunt Jessie dies of a heart attack. Alan is certain that once again his animals will be killed. There is only one chance. And so, aided by two accomplices—Betsy, a classmate, and Dr. Harris, a vet—he attempts a desperate plan to keep his animal kingdom together.