Out of the Dark (The President must Die) - Gregg Hurwitz

As a boy, Evan Smoak was taken from the orphanage he called home and inducted into a top secret Cold War programme. Trained as a lethal weapon, he and his fellow recruits were sent round the world to do the government's dirty work. But the programme was rotten to the core. And now the man responsible needs things to be nice and clean. All evidence must be destroyed. That includes Evan. To survive, Evan's going to have to take the fight to his nemesis. There's just one problem with that. Jonathan Bennett is President of the United States and Evan isn't his only victim. To save himself - and the country - Evan is going to have to figure out how to kill the most well-protected man on the planet...