This disappointing sequel to the Johansens' Silent Thunder (2008) centers on the ancient city of Marinth, submerged in a massive tsunami 4,000 years ago and lying a quarter mile beneath the Atlantic Ocean. The secret that doomed Marinth's civilization to decline before the killer wave is still present and could in the wrong hands be a threat to hundreds of millions of people. As malevolent armsmerchant Vincent Gadiare and his femme-fatale lover, Anna Devareau, maneuver to get their hands on Marinth's secret, Hannah Bryson, world-class submarine designer, gathers her own legion of experts, including her love interest, enigmatic assassin Nicholas Kirov. Entertaining action scenes compensate in part for two-dimensional characters and trite romances. Informed readers may have trouble with the book's lack of verisimilitude. Submarines behave suspiciously similar to aircraft, and photosynthetic plants thrive in the water well below the photic zone. (July) Copyright 2010 Reed Business Information.