Two sisters from Ohio, Ruth and Eileen Sherwood, arrive in New York looking for big success in the big city. Ruth is an aspiring writer, while Eileen is an aspiring actress. They take up residence in a comically terrible basement apartment on Christopher Street in Greenwich Village, in a building owned by the slightly shady Mr. Appopolous.
Immediate success does not follow for the sisters but romantic complications do ensue. The rather sardonic Ruth seems to have unrequited feelings for Robert Baker, an editor at a New Yorker-type of magazine to which Ruth has submitted some of her stories, while the very pretty and charming Eileen is pursued by several men, including a somewhat dorky drugstore clerk, Frank Lippencott, and a salty, slightly sleazy newspaper reporter, Chick Clark. And there also seems to be some attraction between Robert and Eileen.
Tension develops between Ruth and Robert when, after having read her stories, he tells her that she's talented but needs to write about what she knows in her own voice rather than imitating the work of famous writers. Ruth does not take criticism easily.
Hoping to be alone with Eileen, Chick has a newspaper associate call Ruth with a lead on a story: the arrival in New York of a group of Brazilian cadets. If she can write a good story about it, she is told, the paper might publish it and it could be her break as a writer.
Ruth goes to the Brooklyn Navy Yard to meet the cadets, who speak very little English but just enough to make it clear that they want to learn the conga, which they seem to think of as an American dance. Ruth teaches them, hoping that they will then answer her interview questions, but they become obsessed with dancing the conga. A huge conga line eventually brings Ruth and the cadets to Christopher Street. Eileen, whom Ruth has asked to take over leading the cadets and to try to lose them, is arrested when a riot ensues and Act One ends.
In Act Two, Eileen is under arrest in the police station, where she has so charmed all the policemen that they are acting as her servants. While visting Eileen there, Ruth runs into Robert, who has come to see Eileen. Ruth tells Robert that her story about the cadets was rejected by Chick's editor. Robert asks to read it. Ruth gives it to him as she goes off to her new job: handing out flyers and trying to drum up business for the Village Vortex, a club for hepcat types.
Robert likes Ruth's story and takes it to his own editor, who rejects it. Robert feels so strongly about the story that he quits his job. When Eileen, who is now out of jail, learns this, she tells the initially skeptical Robert that he must be in love with Ruth or he wouldn't have quit over the disagreement with his editor. Over the course of the song "It's Love," Robert becomes convinced.
Eileen has been hired to sing at the Village Vortex. In the final scene, which takes us to the Vortex, Chick shows up to tell Ruth that his editor actually does like the story and wants her start work for the paper next week. Eileen is so happy that she starts crying and can't sing. The club owner, Speedy Valenti, threatens to fire her. Ruth suggests that she and Eileen sing together. They bring down the house with their duet of "The Wrong Note Rag," and all ends happil as it's clear that a romance is about to blossom between Ruth and Robert and everyone sings a reprise of "It's Love."
A subplot involves Ruth and Eileen's Christopher Street neighbors, Wreck (a football player unemployed in the summer months) and Helen, his wife. Helen's mother, who is coming for a visit, doesn't know that Helen is married so Wreck temporarily moves in with Ruth and Eileen. All ends happily, with Mrs. Wade (Helen's mother) eventually coming to accept the marriage (after some subterfuge to get her there), and even a possible romance developing between Mrs. Wade and Appopolous.