Everywhere Gray and Barkley swim, fish are whispering of a growing threat, of a shark named Finnivus who will eat anything or anyone, and won't stop until he has seized control of the entire ocean. Finnivus has an armada of vicious battle sharks to help him expand his empire, and Gray realizes that it's up to him to save the Big Blue. But first he must train with Takiza, the wise and mysterious fighting fish who has promised to teach his young apprentice...

"Peace has come to the Big Blue in the wake of evil Emperor Finnivus's death, but danger is not entirely passed. The scheming mako Velenka breaks free from her underwater prison and will stop at nothing to get her revenge"--