In the midst of the German army’s blitz across Europe in May 1940, while Parisians evacuate their city, the chief curator of the Musée de l’Armée receives orders to move a mysterious cargo out of the country. Upon reaching the port of Le Havre and discovering his intended ship sunk, he places the object on a weathered steamer that sets sail amidst German gunfire.
Fast forward to the present day, where the Director of the National Underwater and Marine Agency, Dirk Pitt, discovers an assortment of uncut diamonds during a diving expedition in the English Channel. When these diamonds are stolen, Pitt and the NUMA agency find themselves entangled with a lethal cabal whose plans extend far beyond mere theft. Unveiling a plot with global consequences, the cabal targets crucial water treatment facilities worldwide, placing the entire population in imminent peril.