After losing everything, a young fish, Pi, goes to live with his family on the Reef. There he meets the love of his life but finds that she already has the unwanted affections of a bully shark. He must follow his destiny to save her and rid the Reef of this menace for good.

Trained in the skills of sea power, Pi the fish can fight a shark, sink a squid or batter any random predator that ever threatens his friends and neighbors on the reef. Unfortunately, being the only hero in town can take its toll, especially when a group of sharks declares that the end of the reef is soon at hand.