Charlotte, nicknamed Sprat, lives with her mother and grandmother, goes to school, and loves spending time with her best friends. They've long dreamed of forming their own gang, but then their grandmother goes away on business and entrusts Sprat with the house, garden, and chickens. The girls decide to set up headquarters in the chicken coop, calling themselves the 'Wild Chickens.' Now the girls can fight back against their enemies—the boys from the 'Pygmies' gang, who constantly pester them. On top of everything else, the Chickens must unravel the mystery of the key their grandmother left them for safekeeping, strictly forbidding them to use it. Could it be that their grandmother is hiding treasure?