Dirk Pitt was astonished to discover that he had two grown children he had never known, 23-year-old twins born to a woman he thought had died in an underwater earthquake Both have inherited his love of the sea, and now they are about to help their father in the adventure of a lifetime The two young people are working in a NUMA underwater enclosure off the shore of Nicaragua, trying to determine its origin Then the worst storm in years boils up out of the sky, heading not only straight for them but also for a luxurious floating resort hotel Desperately they, and the NUMA crew, rush to the rescue of the hotel's inhabitants, but what they find in the storm's wake makes the furies of nature pale in comparison