In the small company town of Renwood, secretary Lil "Red" Andrews sets her sights on her boss, William Legendre, Jr., the son of Renwood's leading citizen.  Regarding his happy marriage to childhood sweetheart Irene as only a minor obstacle, Red, who wears Bill's picture in her garter, doesn't want to leave his house after they have been working late there one night.  He tells her to leave because she is "too darn pretty," but weakens when he sees his picture on her garter.  Just as they start to become more familiar, Irene comes home and Red quickly leaves.  An embarrassed Bill insists that nothing has happened and promises never to see Red again.

The next day, Bill's father offers Red a job in Cleveland, hoping to convince her to leave his son alone, but she feigns resentment and demands to see Bill.  Though he is still attracted to Red, he sends her away.

A short time later, when Red sees Bill and Irene at The Log Cabin nightclub, she has him called to the telephone and corners him in the phone booth.  After they kiss, he promises to see her the next evening.  Later that night, however, Irene and Bill reconcile their differences and Bill decides never to see Red again.

The next night, Red gets drunk when Bill fails to meet her, then goes to his house and creates a scene in front of Irene.  After Red leaves, Bill angrily goes to her apartment, then slaps her.  When she tells him to do it again because she likes it, he beats her, then makes love to her.  Soon Irene divorces Bill and he and Red marry.  When Irene comes to see him to see if he is happy, she tells him that their relationship won't last because it is only based on sex.

Because marriage to Bill still has not helped Red to be accepted socially in Renwood, she wants to move to New York.  To further her aim, she seduces visiting New York tycoon Charles B. Gaerste and only reveals her name after they have made love.  She then demands that Bill throw a party for Gaerste and invite the town's leading citizens.  When the party guests leave early to go to another reception at Irene's, however, Red is furious and begs Bill to take her to New York.  Mr. Legendre, who found her handkerchief in Gaerste's hotel room, shows it to Bill, who then lets Red go to New York but threatens to divorce her at the first hint of a scandal.

Red goes to Gaerste in New York and soon becomes his mistress, while at the same time taking the handsome French chauffeur Albert as her lover.  Soon Bill arrives at Gaerste's apartment and shows him suggestive photographs that he has obtained of Red and Albert and says that he is planning to divorce Red.  Gaerste then discharges Albert and tells him to take Red with him.  Desperate, Red then wires Bill that she is coming home; but back in Renwood she finds that he has moved to his father's house and has started seeing Irene again.  Mr. Legendre offers Red a check for $500 to leave town, but she runs after Bill, who is driving away, and shoots him.  Bill recovers from his wounds, however, and refuses to prosecute Red.

Two years later, when the remarried Bill and Irene go to the races in Paris with Mr. Legendre, they see Red, who has become the mistress of a millionaire and a well-known figure in Parisian society.  As Red drives back home with her rich Frenchman, she is chauffeured by Albert.