Armored cars, burner phones, top-notch weaponry and top-secret missions--this is the life of today's private military contractor. Like author Simon Chase, many PMCs were once the world's top military operatives, and since retiring from outfits like US Navy SEAL TEAM Six and the UK's Special Boat Service, they have devoted their lives to executing sensitive and hazardous missions overseas.

Working at the request of U.S. and British government entities...