'Farewell My Valento' : all wartime America tries 'passing' as native born WASP

When an originally dark-haired Italian-American woman successfully 'passing' as Mrs Helen Grayle (an icy blond member of 1940s Los Angeles' upper crust) is threatened with the exposure of her dark (literally : noir) secret , Velma Valento kills and kills and kills again.

All to prevent her secret from ever coming out.

This basically is the engine that drives the plot of the first and greatest noir cum private eye story ever : Raymond Chandler's FAREWELL MY LOVELY (1940).