Abby Hunter plans a birthday cake her brother will never forget. Will she be able to keep it a secret from him? Or will her little sister's big mouth get in the way?As the party day nears, Abby's best friend, Stacy Henry, needs help solving a family mystery. Abby goes broke playing detective. Then, one after another, the Cul-de-sac Kids break out with the chicken pox! What could be worse?.