The Hardy boys are bound on a perilous trouble-shooting mission. Destination: Deep Six, a floating oil rig in the Gulf of Mexico. The brothers have gone undercover -- Frank as a helicopter pilot, Joe as a jack-of-all-trades -- to find out who's trying to destroy the operation, putting four giant rigs and their crews at risk.

The Hardys learn that an eco-terrorist organization is openly opposed to the rigs. But they also find that bad blood in this business flows as thick as the oil, and that the truth may be as treacherous as a tropical storm. They've landed in the middle of a high-seas battle-ground -- a dirty war that could trigger ecological disaster at any moment!