When fifteen-year-old Ty, who has always lived on the ocean floor, joins Topside girl Gemma in the frontier's underworld to seek and stop outlaws who threaten his home, they learn that the government may pose an even greater threat.

Ty discovers an entire township chained to a sunken submarine, its inhabitants condemned to an icy 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.

When Alfie McQuinn, the notorious jewel thief, is killed on a job, his last words to his son, March, are to "find jewels" and this instruction leads the boy to Jules, the twin sister he never knew he had--and the perfect partner to carry on the family business.

March and Jules are teenage twins, following in their father's footsteps as jewel thieves, but when their latest job goes wrong they end up with one jewel, a sapphire called the Morning Star, one of three cursed jewels--and the only way they can break the curse is to elude the FBI, Interpol, and a gang of international criminals, find the other two jewels, and reunite them.