Ty has always known that the ocean is a dangerous place. Every time he swims beyond the borders of his family's subsea farm, he's prepared to face all manner of aquatic predators--sharks, squid, killer whales. . . What Ty isn't prepared to find in the deep is an entire township chained to a sunken airplane, its inhabitants condemned to an underwater grave. It's only the first clue to a mystery that has claimed hundreds of lives and stands to claim two more--lives very precious to Ty and his Topsider ally, Gemma. Now in a desperate race against the clock, Ty and Gemma find themselves in conflict with outlaws, Seaguard officers, and the savage, trident-wielding surfs--plus some of the most deadly creatures the ocean has to offer.