Brian January - Emerald (Park Skarda-April Force #1)

Emerald (#1) Beneath the ruins of a time-lashed temple in the Egyptian desert, two ancient pillars—one made of solid gold, the other of emerald—reveal the existence of an unknown power source, an element so powerful that a single teaspoon could turn an entire city into molten slag.
27,000 miles above the Arctic Circle, a clandestine satellite-based laser weapon readies to boil the polar ice pack to slush, giving access to billions of barrels of oil buried beneath the ocean floor. And inside a remote mountaintop fortress in Crimea, a cult of descendants of a vanished civilization plots to drown the Earth in a planet-wide deluge. All these occurrences have one thing in common: the Emerald Tablet of Thoth, the fabled writings of the legendary priest-king of Atlantis.
Hunted by a psychotic assassin and fanatic followers of the cult, OSR agents Park Skarda and April Force and their brilliant linguist ally Flinders Carlson are plunged into a deadly race against time, a race they must survive at all costs if they are to find the Tablet and keep it out of their enemies’ hands.
From secret chambers beneath the Sphinx to a hidden vault in the bowels of the Vatican to a Nazi U-boat perfectly preserved in the oxygen-starved depths of the Black Sea, Skarda, April, and Flinders pursue a path of danger and death to save mankind from ultimate destruction.