While having fun, a valuable lesson is learned in the fourth book of the "Crystal City" series. Carmella and Sam, both seven years old, and Max who is five years old, are best friends who just happen to be cousins. With the help of an unlikely friend who can fly, they go up above the clouds to a city made of crystals. On this visit, they are told to bring their parents. Once there, they are met by a wise and beautiful lady who appears to be surrounded...