From audible.com:

America’s worst nightmare has just become a brutal reality. The most unlikely terrorist enemy of all now holds a knife against the country’s throat. With both diplomatic and conventional military options swept from the table, the president calls upon Navy SEAL turned Secret Service agent Scot Harvath to disable a brilliantly orchestrated conspiracy intended to bring the United States to its knees.

Teamed with beautiful Russian Intelligence agent Alexandra Ivanova and a highly trained CIA paramilitary detachment, Harvath embarks on an adrenaline-fueled search that spans the world - and leads to a final, deadly showdown on American soil, with a lethal and sinister enemy from the past.