The Machiavelli Covenant

Nicholas Marten's former girlfriend is mysteriously killed along with her child and congressman-husband. A former LA cop, Marten learns her husband had just discovered a secret and illegal bioweapons program. When the feds fail to investigate, Marten pursues the killers himself.
At a NATO summit in Warsaw, President John Henry Harris meets with Europe's heads of state. When Harris learns secret a White House cabal has ordered the German chancellor's assassination, he angrily objects. The cabal not only threatens to kill Harris, they pull the secret service off his detail.