Cloak of Darkness — Helen MacInnes

When Bob Renwick of Interintell, a counter-terrorist agency, discovers his name on the Minus List, it is just the beginning of a riveting tale of suspense that sweeps from London to New York, Washington, Paris, Chamonix, Amsterdam, Zurich, and exotic Djibouti. An international munitions firm is secretly operating training camps for terrorists and supplying everything necessary for violent subversion. It is a hidden and hideous force threatening freedom everywhere. It must be stopped, by a man marked as its victim.