American assassin - Vince Flynn

Before he was considered a CIA-super agent, before he was thought of as a terrorist's worst nightmare, and before he was both loathed and admired by politicians on Capitol Hill, Mitch Rapp was a star college athlete with an untapped instinct for violence.
Tensions in the Middle East are simmering when Central Intelligence Angency Director Irene Kennedy pays a visit to Syracuse University, where she hopes to recruit none other than Mitch Rapp, a student who has quickly climbed up the academic and athletic ranks. At first glance, he appears like any other smart, good-looking American college kid. Under the surface, however, a tempest rages. Tragedy entered Mitch's life a year before when 35 of his classmates, including his girlfriend, perished on Pan Am flight 103. Since then, Mitch has grieved their senseless deaths and has felt helpless in his desire for revenge. When Kennedy arrives on campus, his career path is suddenly laid out for him.
Nine months later, after gruelling training, Mitch finds himself in Istanbul on his first assignment, which is to assassinate the Turkish arms dealer who sold the explosives used in the Pan Am attack. Mitch hits his target but quickly sees, for the first time, what revenge means to the enemy. When Mitch's mentor and a fellow recruit are kidnapped and tortured by a dangerous group of Islamic jihadists, he must stop at nothing to save them.