Peter lives in a silent world. Thirteen, deaf, and tormented by neighborhood bullies, Peter seeks solace in summertime snorkeling outings with his eccentric Viking-horn-helmeted Uncle Sverrir. But after a dangerous encounter with a giant hammerhead predator, Peter discovers he has a unique gift: He can talk to sharks.
Peter quickly learns that the sharks near his Florida home are being mysteriously killed off. They need his help. Thrust into a scary but exciting adventure, both above and below water, Peter is distressed to learn that his dad, a chef, is connected to the crime - being blackmailed by his boss to cook up illegal shark-fin soup. Peter sets himself to the daunting task of saving both the sharks and his father, but to do so, he must rely on the very bullies who have tormented him.