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"--

"As the first Shark Wars series arc draws to a close, hero Gray unexpectedly finds himself the ruler of the ocean. He's got to make wise decisions in a time of upheaval and isn't sure if he's up to the task! Dangerous prehistores are loose in the Big Blue, and Gray must defeat their evil leader, Grimkahn. But if he is to do that, he and Barkley must first outsmart the sneaky and dangerous frilled shark, Hokuu..."--Publisher's website.