ACT I
Millie Dillmount, a young woman from Kansas with big ambitions, runs away to Manhattan in 1922, amidst the "Roaring Twenties." She has her sights on becoming a fashionable, "modern" city woman. Her excitement is palpable as she cuts her hair into a signature bob. Millie receives an almost immediate wake up call when she is mugged, losing her purse, scarf, hat and even shoes. Feeling desperate, Millie trips Jimmy Smith, a handsome, up-scale man. Instead of helping Millie, Jimmy suggests that she finds a room at Hotel Priscilla. Millie does take his advise and quickly books a room for herself at the Hotel Priscilla.
The scene shifts to the Hotel Pricilla, while largely serves wanna-be actresses and young, single women. The girls at the hotel discuss the leading story in the daily newspaper, "White Slavery." Ethel explains that young orphans are disappearing. Soon, the sinister hotel owner and slave trader, Mrs. Meers, delivers Ethel a telegram. Ethel's great uncle has died and she has no living relatives left.
Mrs. Meers soon confronts Millie about her late rent and threatens to kick her out of the establishment. Fortunately, Millie then meets Dorothy Brown, a rich, young woman who wants a glimpse into how the other half lives. Millie and Dorothy agree to split a room, but Mrs. Meers insists that Dorothy can take Ethel's old room. When Millie asks what has become of Ethel, Mrs. Meers states that she has been offered an acting job in "the Orient."
One of Mrs. Meer's employees, a Chinese immigrant who is working tirelessly to bring their family to America, is tasked with drugging Dorothy. As soon as Ching Ho sees Dorothy, he immediately falls in love with her and is unable to give her the drugged apple. Millie, who has just landed a job, enters and whisks Dorothy away for a night at a speakeasy to celebrate with the other girls from the hotel.
Millie and the girls run into Jimmy outside of a speakeasy, he helps the girls in and dances with Millie. The club is soon raided and Jimmy and Millie get to know eachother better inside a jail cell. Jimmy realizes he is falling in love with Millie, but she tells him her boss is her fiance.
Jimmy invites Millie to an elite party. Jimmy and Millie soon get into an argument, which ends with Jimmy kissing Millie. At this moment, Millie realizes she is falling for Jimmy. Unfortunately, later that night she sees Jimmy sneaking out of Dorothy's room and she imagines the worst.
ACT II
Millie refuses to answer any calls from Jimmy at her job at Sincere Trust, but she is clearly still in love with him. The other women who work there try to convince her to move on and "forget about the boy." Millie has set her sights on Graydon, but has had little success thus far. Her plans are further set back when Dorothy visits her at work. Dorothy and Graydon immediately hit it off. Meanwhile, Jimmy climbs in through Millie's window and asks her to dinner. Millie confronts Jimmy about exiting Dorothy's room, but he explains that he was asking for her advice about his feelings for Millie and Millie agrees to have dinner with him.
Meanwhile, back at the hotel, Mrs. Meers continues to plot against Dorothy and convinces Ching Ho, who is still in love with Dorothy, to help with her scheme in order to bring his mother to America.
At dinner, Jimmy admits that he loves Millie but Millie doesn't want to marry a poor man. She eventually decides that she would rather marry for love than for money. She is about to reveal her feelings for Jimmy, when she encounters a distraught Graydon. He is drunk and upset because Dorothy has stood him up for their dinner date. He even check the hotel, but Mrs. Meers stated that she had already check out. Jimmy and Millie realize that something terrible has happened and call on their friend, Muzzy, for help.
Muzzy disguises herself as an orphan and introduces herself to Mrs. Meers. Muzzy catches Mrs. Meers, who is revealed to be an old chorus girl Daisy Crumple, in the act and a hidden Millie transcribes the whole conversation. Meanwhile, Ching Ho has rescued Dorothy and Mrs. Meers is escorted to the police station by the hotel girls.
Jimmy proposes to Millie, and even though he is poor, she accepts. In a whirlwind of revelations, Millie finds out that Jimmy is Muzzy's rich step-son, Herbert J. Van Hossmere III and Dorothy is his heiress sister, Dorothy Carnegie Mellon Vanderbilt Van Hossmere.
