The Trimoni Twins and the Changing Coin

Eleven-year-old twins Beezel and Mimi -- talented magicians who use their Changing Coin to transform people and animals into other creatures -- so happily accept a magic challenge from the Great Paparella, but when the girls begin to fear that he may be up to something evil, they have to keep their wits about them to keep their prized possession from getting snatched away.