Deep below the deceptively beautiful waters of the Atlantic Ocean, guarded by hundreds of dolphins, lie the astonishing remains of a mysterious lost city much like the legendary Atlantis. Marinth's sudden disappearance has confounded scientists for years, but now, with the revelation of a key artifact, Hannah Bryson realizes that the long-buried city's explosive secret could have dire consequences for the modern-day world. But she isn't the only one who realizes it. The artifact is hijacked, and Hannah stands alone between a power-hungry enemy and widespread destruction.