Socialite Pat Reynolds (Ida Lupino) is forced to become the "smart girl" of the title when her wealthy father commits suicide, leaving nothing but a pile of debts. Pat sets up a successful hat-designing business, providing the sole support for herself and her sister Kay (Gail Patrick). So devoted is Pat to Kay's welfare that she stands by in stoic silence as Kay begins romancing Pat's sweetie Nick Graham (Kent Taylor). But a quick glance at the billing order of the stars should be indication enough as to which sister ends up with Nick at the fade-out. Comedy relief is provided in ample doses by old-timer Joseph Cawthorn and bespectacled crooner Pinky Tomlin, cast as father-and-son haberdashers.