Celtic Empire - Clive Cussler, Dirk Cussler

A deadly river collision puts Dirk Pitt on the trail of an ancient mystery stretching back thousands of years . . . When a rogue cargo freighter strikes an oil tanker in the Detroit River, the oil spill is the worst marine disaster in years. Dirk Pitt's NUMA team lead the clean-up operation, with the help of new green tech firm, BioRem. But when one of NUMA's best divers dies suspiciously while working on the wreck, Pitt fears there's more to BioRem than simply saving the environment. Discovering a trail of unexplained deaths which appear to be linked to BioRem's sites around the world, Pitt unravels a mystery from our past that could jeopardise mankind's future. But someone is determined to make sure Pitt and his associates don't survive to learn the truth . . .