ALEXANDRA Dean's documentary, Bombshell: The Hedy Lamarr Story (12A), will be shown City Screen, York, on March 8 at 6.30pm to mark International Women's Day.

The film focuses on the little-known back-story of screen icon Hedy Lamarr. Although renowned internationally for her silver-screen exploits, the Austrian actress – born Hedwig Eva Maria Kiesler – also became a pioneer in the field of wireless communications after her emigration to the United States. Her father was of Jewish extraction but both Mussolini and Hitler attended lavish parties at the home of her first husband.

During the Second World War, Lamarr and co-inventor George Anthiel developed a "Secret Communications System" to help combat the Nazis. By manipulating radio frequencies at irregular intervals between transmission and reception, the invention formed an unbreakable code to prevent classified messages from being intercepted by enemy personnel.

Nowadays, frequency hopping is used with wireless phones, GPS, most military communication systems, and without Hedy Lamarr we would not have Bluetooth and Wi-Fi.

The film screening will be followed by a satellite question-and-answer session from the BFI in London featuring actress Susan Sarandon and the film's director, Alexandra Dean.

Tickets are on sale at or on 0871 902 5726.