Labyrinth Of Fire by Keith Robinson
Hal Franklin and his friends have made it safely into Miss Simone's world. As shapeshifters, some of them are looking forward to meeting their alternate kind. But others dread the prospect.
Dewey, for instance, quickly feels the pressure of being a centaur. Meanwhile, Lauren and Hal are quaking in their shoes. The village in the north is under constant attack from harpies and dragons, and these vicious creatures must somehow be reasoned with and persuaded not to plunder and steal, and most importantly, not to eat humans! The trouble is, neither harpies nor dragons are interested in negotiating.
Hal and his friends join forces to deal with these serious issues. They end up in the heart of dragon country, down in the Labyrinth of Fire beneath an oozing volcano. Somehow they must make the dragons see the error of their ways. Their quest forces them to question the extent of their shapeshifting abilities... and this leads to a shocking discovery that is likely to start a war.