A cabaret singer goes back to work to help her husband get a life-saving operation, but her relationship with a millionaire breaks up her marriage.
In Germany American hikers discover seven actresses bathing. Helen (Marlene Dietrich) tells Ned Faraday (Herbert Marshall) to leave, but he refuses. In New York Helen bathes her boy Johnny Faraday (Dickie Moore). Ned offers to sell his radiated body to Dr. Pierce, who says he can get treatment in Germany for $1500. Helen and Ned tell Johnny the story of how they met. Helen tells Ned she could go back to the stage to earn the $300 he needs to get to Germany. Helen gets an interview with agent Ben Smith (Gene Morgan), who takes her to Dan O'Conner (Robert Emmett O'Connor). Helen performs as Blonde Venus, and Taxi Belle (Rita La Roy) tells her she got a bracelet from Nick Townsend (Cary Grant) for a favor. Amid African dancers Helen strips off a gorilla suit and sings "Hot Voodoo." Nick goes back to meet her and asks her out. Helen gets a $300 check from Nick that enables Ned to sail to Germany.
Nick gives Johnny a puppy. Ben tells Dan that Helen is married and gone, and Ned calls that she quit. Nick gives Helen an apartment and kisses her. Helen tells Nick that Ned is returning in a month, and they go away for two weeks; but Ned returns early and looks for Helen. She comes back, and Ned asks where Johnny is. Helen tells Ned that she got the money from a man and suggests going on; but angry Ned wants Johnny. Ned goes to the police to search for Helen and Johnny. Helen sings "You So-and-so." Police call Ned that she is performing in Baltimore. Helen is warned to leave and takes a train. She washes dishes for a meal, is charged with vagrancy, and is followed. She flees with Johnny but lures a detective (Sidney Toler) for a beer and to her room. Helen gives up her son, saying she is no good. Ned arrives, embraces Johnny, and gives Helen $1500, saying he sold his rights to pay her for his life. Helen watches Ned and Johnny leave on a train.
Helen wanders and gives a destitute woman the $1500; but she performs and works her way to Paris, where Nick finds her. Helen sings "Do You Think I'd Care?" and tells Nick she has no cares. He invites her to go to America, and Ned reads news that she is engaged to a millionaire. Ned tells Nick that she can't see Johnny, but he offers Ned $10,000 for ten minutes. Ned lets her see him for nothing. Johnny hugs her and asks them for the story of Germany. Helen sings him to sleep and asks to stay with Ned, who says she belongs there.
Helen sells herself to save her husband and almost loses him in the intimacy of that process, but their love for their son re-unites them.