In the small California town of Santa Vista, 8-year-olds Amy, Marion, Liz, and Ellie each have their own distinct personalities and interests, but one thing the girls have in common is a serious love of animals. With the help of an eccentric millionaire and the town vet, the four best friends help found and maintain the Critter Club, a rescue shelter set on saving "lost and lonely" animals. Along the way, the girls encounter and navigate a variety of relatable elementary school experiences.