It was a blind ad in a newspaper that caught Tony Mendez’s eye in 1965. The ad (“Artists to Work Overseas — U.S. Navy Civilians”) did not identify the employer, but it carried the whiff of adventure.

At the time, Mendez was working for Martin Marietta (now Lockheed Martin) in Denver, making technical drawings of the wiring harnesses for missiles. It was not the most exciting task. At the time, ...