Under Cloak of Darkness — I. Michael Koontz

Under Cloak of Darkness, a gripping 1950s Cold War thriller featuring ex-FBI agent John Apparite. After being recruited by an ultra secret organization whose existence is known only to elite D.C. brass and whose religion is to kill or be killed, Apparite undergoes weeks of rigorous training that includes a practice brawl with barroom toughs and a butcher shop massacre of Mafiosi selling scandalous photos of his hero, J. Edgar Hoover. Apparite's new boss, the inscrutable, super patriotic Director, orders him to liquidate Robert Kramer, an atomic scientist living in London who possesses the secrets of rocket-firing submarines, before Kramer defects to the Soviets. Apparite soon finds himself caught up in a violent world.