"Any girl can be glamorous," the actress Hedy Lamarr once said. "All you have to do is stand still and look stupid." It's a withering observation, especially for a Hollywood star once known as "the most beautiful woman in the world." Beauty brought Lamarr fame, at least until everything fell spectacularly apart; as with too many actresses, beauty was also her gilded cage. The new documentary "Bombshell: The Hedy Lamarr Story" shows how hard and how long she struggled to escape it - including through her invention in the 1940s of a groundbreaking communication system that underlies modern encryption.