Excerpt of transcript:

Hollywood is a place where folks are often recognized more for their looks than their talent - and actress Hedy Lamarr was no exception. But it's what she invented in her spare time - to help end that war - that has history turning a kinder eye, linking her to a bombshell of a whole different sort. Lee Cowan reports:

She possessed the kind of beauty that was haunting - an almost smoldering sensuality, with an exotic accent to match.

Even her name - Hedy Lamarr - sounded dark and mysterious. But although she shared the screen with Hollywood legends like Clark Gable, Spencer Tracy and Jimmy Stewart, people rarely remember Hedy's talent.

Most remember only her face - a regret she carried with her to her grave.

"The boys abroad, during the Second World War, voted her the most desirable, beautiful actress or pinup that they could possibly see," said writer Richard Rhodes. "So she had a great deal of fame and fortune, but not that inner satisfaction that she wanted in life."

Rhodes is an author best known for his Pulitzer Prize-winning work on the making of the atomic bomb - but his most recent book about Hedy Lamarr is just as explosive.

So what got a science writer interested in a half-forgotten celebrity? Quite simply, Hedy's other side - the intellectual side - and had it turned out, it might have been the blueprint for success far beyond Hollywood.

To the untrained eye the drawing is just a maze of wires and switches. But to Richard Rhodes, it was genius. What surprised him most, he told Cowan, was "the sheer inventiveness of the invention."

It was Hedy's idea for a radio-controlled torpedo, guided by a signal that couldn't be intercepted - a technology she called "frequency hopping."

"The first question always is, "What? A Hollywood star? What was she doing inventing some piece of electrical engineering?" said Rhodes.

Her life reads like a Hollywood script: The glamorous movie star by day was, by night, the lonely immigrant channeling an inner Thomas Edison.

"She set aside one room in her home, had a drafting table installed with the proper lighting, and the proper tools - had a whole wall in the room of engineering reference books." That, Rhodes said, was where she "invented."

It was a hobby that remained obscured in the shadow of her celebrity - one she rarely revealed, even to her own son, Anthony Loder: "She was such a creative person, I mean, nonstop solution-finding. If you talked about a problem, she had a solution."

Looking back, Loder - the product of the third of Hedy's six marriages - says his mother's tinkering may have been an escape.

"She wanted to stop all the Hollywood stuff which she didn't really enjoy," he said.

Most of Hedy's inventions - including a better Kleenex box and a new traffic signal - never really went anywhere. But her idea for that torpedo got a patent...

...But Rhodes said when the Navy brass looked at the invention, "They...threw it on the back shelf. The Navy's response really was, 'You should go raise money for the war. That's what you should be doing instead of this silly inventing.'"

So Hedy did precisely that, using her celebrity to raise millions in war bonds - dismissed again for her brains in favor of her beauty.

As time went on, she tried television, but it never fit, and her star slowly faded.

But her notion of "frequency hopping" became the basis for most modern WiFi technology.

"Today, frequency hopping is used with the wireless phones that we have in our homes, GPS, most military communication systems - it's very widely used," said Rhodes.

But it was those building on her idea who got the credit. Hedy had quietly signed her patent over to the Navy, and left it at that. She gave the technology away, and never made a dime off of it.