When Finn Kennedy comes to live in Dubai he expects to do nothing more adventurous than surf a few good waves. Then he meets Triton, the good Sea Djinn, a supernatural being with spectacular powers. Triton reveals that Finn’s parents have been kidnapped at sea by Hydrus, the evil Sea Djinn, who is preparing to wage war against Triton’s and Finn‘s world in a battle of the Djinn that has been brewing for a thousand years. Triton recruits Finn to his army and bestows on him some of his own powers. Finn, together with his cousin, Georgina, and his friend, Fred, prepares to travel to the underwater lair of Hydrus, far across the sea in the Dark Kingdom, to rescue his parents and to fight Hydrus.