Mae West adapted her play Diamond Lil in this melodramatic comedy about a diamond-studded singer and her mostly criminal friends.
Dan Flynn (David Landau) wants to get Gus and become boss so he can have Lady Lou. Gus Jordan (Noah Beery) complains to Salvation Army Captain Cummings (Cary Grant) about his driving away his customers by reforming them. Rita (Raffaela Ottiano) and Sergei (Gilbert Roland) assure Gus they will keep their scheme quiet. Lady Lou (Mae West) tells her maid she wasn't always rich; there was a time when she didn't know where her next husband was coming from. She welcomes Rita back and is pleased to meet the suave Sergei. Sally (Rochelle Hudson) tries to kill herself; but the understanding Lou helps her. Lou says, "When women go wrong, men go right after them." Rita offers Sally a position on the Barbary Coast. Cummings helps the fugitive Pete by giving him an alibi, and Lou backs him up. She asks Cummings to come up and see her sometime, concluding he can be had.
Lou visits Chick Clark (Owen Moore) in prison, where he has been for stealing diamonds for her. He complains and is jealous, but she says she'll wait. Spider tells Lou it was Dan who turned in Chick. Since the mission next door is about to close for lack of rent, Lou buys the building from Jacobson for diamonds worth $12,000. Lou sings "Easy Rider" on stage. Dan tells Lou he is moving in when Gus is "sent up the river" and that there is a private detective around called the Hawk. Spider tells Lou that Chick broke out of prison. Cummings asks Lou about Sally and says her diamonds have no soul.
Gus gives Rita and Sergei counterfeit money to spend. The police are looking for Chick, who climbs in Lou's window. Lou tells him to get out; he begs, and Lou promises to meet him later. While a woman is accusing Rita, Sergei gives Lou a diamond pin. Rita sees him kiss her; after Sergei leaves, she pulls a knife on Lou but is killed in the tussle. The police search for Chick and leave. Cummings has Sally talk to the district attorney. Gus tells Lou he is jealous of Sergei. Spider got rid of Rita's body and takes Chick to Lou's room. While Lou is singing "Frankie and Johnny," Chick shoots Dan. Cummings arrests Gus. Lou realizes he is the Hawk and calls him the lowest. Sally identifies Sergei, who is arrested. Chick is about to kill Lou when he is arrested along with her; but Cummings takes Lou in a carriage and says her diamonds are going to the storehouse; giving her a ring, he promises to be her jailer for a long time as they kiss.
Mae West makes excellent use of innuendo, and her character Lou is easily transformed from diamonds to soul by the reforming Cummings.