The Monster Book Chronicles — J.C. Fuller

Legends and stories have been told of the world's worst fifty monsters and creatures and how they caused havoc and destruction until being bound magically into a book by eight wise wizards. Several centuries later as the legends and stories become lost a group of six children led by Bruce Jones find the magic book of monsters. Not knowing of the book's content Bruce Jones and his friends release the fifty monsters and demons into the world. Realizing that peace can't be obtained until all the monsters are caught and sealed again Bruce and his friends journey through several countries around the world including the US, UK, France, Germany and more as they search for the fifty monsters.