Act I is set in a garden outside of a country cottage, rented by the determined, self-confident, and well-educated recent college graduate Vivie Warren. Vivie is approached by Mr. Praed, an artistically inclined friend of her mother’s. Vivie is a gifted mathematician and tells Praed she plans to live a practical life, going into business with her friend Honoria Fraser and working in law, insurance, and finance. Praed advocates for a life of aesthetic appreciation, but Vivie replies that she has spent time with artistic people at concerts and museums and was bored. She asks Praed if he thinks her mother will approve, explaining that she has always lived away from her mother and knows little about her. Praed refuses to tell Vivie much about her mother. Vivie predicts that her mother may try to control her life, but says that she will use her mother’s secrecy about her own life against her in any argument they have about Vivie’s future.
The loud and gaudily dressed Mrs. Kitty Warren and the rich, middle-aged playboy Sir George Crofts arrive. Vivie goes into the cottage. Praed tells Mrs. Warren that Vivie seems mature and that Mrs. Warren should treat her with respect. Mrs. Warren scoffs that she knows how to treat her own daughter. Mrs. Warren leaves the two men alone, and Crofts asks Praed if he knows who Vivie’s father is. He says he feels attracted to Vivie, but can’t be sure that he isn’t her father. Praed says he knows nothing about that side of Mrs. Warren’s life, but since Crofts is old enough to be Vivie’s father he should treat her in a parental way.
Crofts goes inside and Praed is greeted by an old acquaintance, Frank Gardner. Frank is a handsome, clever man of twenty. He confides to Praed that he is broke and living at home to save money, and that Vivie loves him. Praed invites Frank to tea, but as Frank is entering the cottage his father, the Reverend Samuel Gardner calls to him. Reverend Gardner is a pompous loudmouth who is obsessed with respectability. He demands to know the social station of the people in the house before he will enter their garden. Frank tells him that the cottage is Vivie Warren’s, and that he hopes to marry her. Vivie, he says, has both brains and money, while he has neither. Reverend Gardner says disapprovingly that it’s hard to believe anyone has enough money to support Frank. Frank refers to a story Reverend Gardner told him about his own behavior as a young man: Reverend Gardner offered a lover fifty pounds to buy back his letters to her, so that he could destroy evidence of their affair. Vivie comes outside and is introduced to Frank’s father, and then calls for Mrs. Warren to come outside. Mrs. Warren recognizes Reverend Gardner, who is shocked to see her. She says she still has the letters he wrote her.
Act II takes place inside the cottage that night. Mrs. Warren and Frank are the first to arrive back after a night stroll. Frank flirts with Mrs. Warren, and she kisses him, but then says she meant it in a motherly way. Frank tells her he is courting Vivie. Crofts and Reverend Gardner enter, and Mrs. Warren impatiently asks where Praed is. Frank says he must be enjoying walking alone at night with Vivie. Crofts and Reverend Gardner both object to Frank courting Vivie. Mrs. Warren says she sees no reason why the two young people shouldn’t marry, but when she hears that Frank has no fortune, she says it is out of the question that he marry her daughter. Frank says he will try to win Vivie’s love despite the older generation’s warnings not to. Vivie and Praed arrive and the older people go into the small kitchen to have dinner. Vivie and Frank mock the older generation. Vivie says she hopes never to live a lazy, aimless life like theirs, while Frank says he wants to be idle, but to do it in style. He tries to flirt with Vivie, but she rebuffs him. Vivie and Frank go into the kitchen to eat, and Mrs. Warren and Crofts enter the room. Mrs. Warren says she doesn’t like how Crofts is looking at Vivie. He tells Mrs. Warren that he wants to marry Vivie and suggests that few other men would accept Mrs. Warren as a mother-in-law. Mrs. Warren is disgusted at the idea. Crofts offers to pay her a check on the day of the wedding and then to leave all his money to Vivie when he dies. Mrs. Warren insults him, and he storms out of the house. Soon after, the Gardners leave, taking Praed and Crofts to stay at their home as guests.
Left alone, Mrs. Warren tells Vivie that she thinks Frank is a good-for-nothing and Vivie shouldn’t encourage him to court her. Vivie agrees, adding that Crofts also seems like a good-for-nothing. Mrs. Warren is shocked at Vivie’s self-confidence; she says Vivie will have to see Crofts frequently because he is a friend of hers. Vivie asks whether her mother expects they will be together much going forward, saying she doubts Mrs. Warren will like her way of life. Angry at Vivie’s independent attitude, Mrs. Warren proclaims that she will determine Vivie’s lifestyle. Vivie demands to know her mother’s identity and who her father is, saying she wonders what right her mother has to dictate her life. Mrs. Warren assures her Crofts is not her father, but will not say who is, nor will she say more about herself. Feeling they have reached a dead end, Vivie says they should go to bed. Mrs. Warren accuses Vivie of being heartless and a bad daughter. Vivie says she wants to be treated with respect and will respect her mother’s own choices about her life in return. Mrs. Warren scoffs at the idea that she had any choices and decides to tell Vivie about her life.
Mrs. Warren tells Vivie that she was one of four daughters of an unmarried woman with four daughters who supported herself by taking lovers. Mrs. Warren’s two half-sisters grew up to be respectable women: one died of lead poisoning from work in a factory, while the other married an alcoholic and lived in poverty. Her sister Liz ran away from their school. Years later, when Mrs. Warren was working long hours for low wages in a bar, the two sisters met again. Liz had become a prostitute and urged her sister to do the same. She lent Mrs. Warren money to start work and they eventually set up a chain of brothels across Europe together. Liz now lives the life of a respectable, upper-class woman. Mrs. Warren defends her decision to go into sex work, saying it was the only opportunity a woman like her had to earn a reasonable living. She says that while upper-class women try to marry rich men, lower-class women can only hope to sell their bodies for sex—but marriage and sex work are ultimately very similar. Despite knowing she is supposed to be ashamed of her work, she expresses pride at having kept her self-respect and managed her brothels well. Vivie admires her mother’s grit and truthfulness. Before they say goodnight, Vivie promises to treat her mother lovingly, Mrs. Warren blesses her daughter, and they embrace.
Act III takes place the next morning in the garden outside of the rectory where Reverend Gardner lives and works. Reverend Gardner comes outside and greets his son. He is hung over after staying up late telling scandalous stories with Crofts, and hardly remembers what happened the night before. Frank tells his father that he told Crofts to bring the Warrens over to the rectory, and Reverend Gardner is horrified to hear that people of questionable respectability will be coming to his home. Praed enters and he and Frank watch Crofts, Mrs. Warren, and Vivie approach. Frank is disgusted to see mother and daughter walking arm in arm. When the guests arrive, Frank suggests that his father show them the church. Once he is left alone with Vivie, he asks her why she was embracing her mother. Vivie says she now understands her mother. Frank says that, unlike Vivie, he can see that Mrs. Warren is an immoral person. He flirtatiously tells Vivie that she must not go live with her mother because it will ruin their time together. Vivie briefly falls under his spell.
Crofts approaches and asks to speak to Vivie alone. Frank leaves, but says he will return if Vivie rings a bell in the garden. Crofts makes a very unromantic proposal to Vivie, describing himself as a rich man who knows how to pay for what he wants and will leave her his fortune when he dies. When Vivie refuses him, he says that he was a good friend to her mother by lending her the money to start her business. Vivie is shocked and says she thought that her mother had wrapped up the business. Crofts scoffs at this, saying it would be stupid to wrap up a business that is doing so well. Crofts pretends that the business they are discussing is a chain of bars in Brussels and Ostend, but Vivie reveals that she knows what the business really consists of. Crofts curses Mrs. Warren for telling Vivie, then says that everyone in the upper class profits from exploitative businesses. He points out that Vivie has always lived on money earned in brothels. Vivie is conscience-stricken and tries to leave the garden, but Crofts stops her. She rings the bell, and Frank approaches with a rifle in hand. Out of spite, Crofts tells Vivie and Frank that they are both children of Reverend Gardner. Revolted, Vivie points Frank’s gun at herself, and he drops it. Vivie runs away, telling Frank she is going to her friend Honoria Fraser’s chambers in London.
Act IV takes place in the London office of FRASER AND WARREN, where Vivie is now working. Frank comes to visit Vivie and define their relationship. Vivie says she wouldn’t want to be anything more than a sister to him. Frank believes this means she has found a new boyfriend, which Vivie denies. Praed arrives to bid Vivie goodbye before going to Italy. He says he wishes he could convince her to travel and experience the world’s beauty. At his mention of Brussels, however, Vivie becomes stricken. She reveals her mother’s true profession to Praed and Frank, both of whom are shocked. Vivie goes into the next room to collect herself, and Frank tells Praed that he will no longer try to marry her: he cannot accept money earned from brothels.
Mrs. Warren arrives, looking very nervous. Praed and Frank depart, after Frank leaves a note for Vivie. Vivie has returned her allowance to her mother’s bank and says that she intends to support herself from now on. Mrs. Warren tells Vivie how rich she is and how easily she can buy Vivie a place in fashionable, respectable society. She says she thought that she and Vivie had worked everything out. Vivie asks her mother why she didn’t leave the profession once she had made enough money to live. Mrs. Warren says she needs work to keep busy and explains that since someone will always do what she does, she does no harm to anyone by continuing in her business. Vivie says she cannot respect the way her mother lives. Mrs. Warren curses Vivie, saying she stole her education and now refuses to do her duty as a daughter. She leaves, refusing to shake Vivie’s hand. Vivie sits down at her desk and, with a sigh of relief, becomes engrossed in her work.
