End Game by Baldacci, David

Two of the government’s most lethal assassins scour rural Colorado to find their missing handler–and discover an insidious and lethal threat along the way in this New York Times bestselling thriller.

Will Robie and Jessica Reel are two of the most lethal people alive. They’re the ones the government calls in when the utmost secrecy is required to take out those who plot violence and mass destruction against the United States. And through every mission, one man has always had their backs: their handler, code-named Blue Man.

But now, Blue Man is missing.

Last seen in rural Colorado, Blue Man had taken a rare vacation to go fly fishing in his hometown when he disappeared off the grid. With no communications since, the team can’t help but fear the worst.