Marilyn Monroe becomes an undercover spy, ditching her diva image to infiltrate criminal circles. Her sparkly black dress hides secret pockets with miniature weapons (a short-barreled pistol or a hidden knife). 
Instead of singing, she uses charming conversation to extract information, and her hat contains a listening device.  
Jane Russell is her partner, a tough detective who leads the field investigations. Her elegant floral suit hides a fighting gear: a rope belt and a retractable baton. She's the one who gets into the physical action, breaking down doors and confronting gangsters.