Blood Lines by Nelson DeMille

Army Criminal Investigation Agents Scott Brodie and Maggie Taylor are reunited in Berlin and tasked with investigating the murder of one of their own: CID Special Agent Harry Vance of the 5th MP Battalion, an accomplished counterterrorism agent who had been stationed in western Germany, and whose body was discovered in a city park in the heart of Berlin’s Arab refugee community.

The authorities suspect this is an act of Islamic terrorism, but Brodie and Taylor soon believe there is more to this case. The reason for Vance’s presence in Berlin is unknown, but in looking into his movements prior to his murder, they delve into the many conflicts and contradictions of modern Germany, from the dark legacy of the Cold War to the imminent threat of a rising neo-Nazi movement. And as both the German and American authorities keep a watchful eye on their activities, a new threat emerges from American intelligence agents who fear the duo might have learned too much about US clandestine operations during their previous mission in Venezuela.

Ultimately, Brodie and Taylor realize that the murder of Harry Vance was merely the prelude to a much more sinister future event – unless they can unravel the mystery in time to stop it.