It was the assignment of a lifetime. . . . Brilliant marine architect Hannah Bryson has been given a priceless opportunity. A U.S. maritime museum has just acquired the former pride of the Soviet fleet, the decommissioned submarine Silent Thunder, for public exhibition. Hannah must inspect every single inch of this legendary nuclear attack sub and design modifications that will make it safe for the thousands of expected visitors. Enlisting the aid of her brother, Connor, they examine the enormous vessel and delve into its long and lethal history. But it was a trap. . . . On a routine check, Connor discovers a mysterious message behind one of the ship’s panels. But before he can figure out what it means, there’s a deadly assault on Silent Thunder.