Ready to Kill — Andrew Peterson

When a mysterious note referencing a top-secret US operation is tossed over the wall of the embassy in Nicaragua, Nathan McBride and his old pal Harv are called out of retirement by CIA Director Rebecca Cantrell and sent to Central America. Cantrell wants the situation resolved quickly and knows that Nathan is the man to do it; after all, he has a history with the place. The jungle he and Harv are about to land in is the same one that Nathan barely escaped with his life decades before, an ordeal that left him physically and psychologically scarred. To make it out alive a second time, Nathan will have to face down his own demons and square off with a ruthless killer who learned from the best, Nathan himself.