She became a star in European movies as a teenager, shocking the world with nude scenes in the movie "Ecstasy". Married at 19 to an arms manufacturer (Fritz Mandl, also of Jewish descent) who isolated her in their mansion and kept tabs on her by having her accompany him to meetings with technical staff and unsavory business partners. It was during these meetings that she made her first acquaintance with military technology. Her husband entertained lavishly and stupidly. Guests at his opulent soirees included Benito Mussolini and a certain Adolph Hitler. Important customers, no doubt, but problematic for obvious reasons.
Hedy escaped to America, either by dressing as her maid, or drugging and eluding her maid. Whom should she meet on the boat going over but movie mogul Louis B. Mayer? Hollywood, next stop.
She pursued her hobby of inventing while making movies Like "Algiers" and "The White Cargo". It was during this time that she came up with her breakthrough. In collaboration with her neighbor, George Antheil, an avant garde composer and writer of film scores, Lamarr received a patent for an early form of radio frequency-hopping .
The two arranged a demonstration for the Navy pitching the invention as an unjammable way of guiding torpedoes. The Navy laughed at the pair, mocking the idea that their creation, which used player-piano technology would be able to withstand battle. They suggested she could be more useful to the War effort by selling War Bonds. She took that on, selling seven million dollars worth at one event according to Wikipedia.
Hollywood has no use for aging actresses. That sad fact and botched plastic surgery sent her career into decline. Hedy exiled herself to isolation in Florida, where she died in 2000. Her frequency-hopping idea is the basis today for wireless networking like Bluetooth and Wi-fi.