Celtic Empire: Dirk Pitt #25 (The Dirk Pitt Adventures)

When NUMA’s routine mission in South America uncovers the murder of a United Nations scientist and a troubling pattern of mysterious deaths tied to water testing, Dirk Pitt realizes something sinister is afoot. His quest leads him from the banks of the Nile to the misty lochs of Scotland and the rugged isles of Ireland as he chases a conspiracy with roots reaching back three thousand years.