Dirk Pitt battles his most dangerous foe ever – with help from a very unexpected source. Long hailed as the grandmaster of adventure fiction, Clive Cussler has continued to astound with the intricate plotting and astonishing set pieces of his novels. Now, with a surprising twist, he gives us his most audacious work of all. At the end of Valhalla Rising Dirk Pitt discovered, to his shock, that he had two grown children he had never known, 23-year-old fraternal twins born to a woman he thought had died in an underwater earthquake. Both have inherited his love of the sea- the girl, Summer, a marine biologist- the boy, himself named Dirk, a marine engineer. And now they are about to help their father in the adventure of a lifetime.