Defenders of Central City, Book 4: Secret of the Leviathan

This story is based off of the School of Dragons expansion pack Secret of the Leviathan. When the baby dragon that hatched gets scared and flees from Berk, it is up to Shannon, Skulder, and Phlegma the Fierce to retrieve the dragon before it gets itself hurt. Join the Viking trio as they journey to a strange island with a mysterious labyrinth. And the question that remains is what is the secret of the leviathan?