Bobby Roper and the Nemesis Staff

After being kidnapped by pirates and having their inflatable raft almost swamped by a vicious storm on the ocean, Bobby Roper and his friends find themselves in an unimaginable situation. There are more worlds out there than the Earth and they discover that Bobby is the guardian of those worlds. The other five worlds are: Aery, the dragon world home of the Terragriff dragon riders and the giant Varagons who ride massive black dragons, Amadon, world of the sorcerers, Balsol, world of the Eban Wizards, Silken, world of the Elves, and Haven, secret world of the Guardians
A powerful sorcerer, accompanied by a group of dark sorcerers, is planning to take control of the Ring of Worlds and Bobby, with his newly-found untrained powers, is the only one who can stop them. If the dark sorcerer succeeds he will also rule Earth and use the people as slaves. The people of Earth have no magical abilities of their own to protect themselves.
The safety of the Earth and all of the peoples in the Ring of Worlds depends on Bobby. As if that isn’t enough, Bobby feels responsible for the safety of his friends who are accompanying him, and, he must find the Nemesis Staff before it destroys him. Bobby is only twelve years old and he wants nothing more in the world than to be back home with everything back to normal.