It is September 1, 1870. Dove feels intensely lonely in her marriage to Old Man Sing. He confines her either to their apartment or his shop, where he displays her beauty to attract customers but forbids her from even looking out a window. Dove spends her days embroidering in the shop, hoping that Petal might one day visit. Her only connection to the outside is with Moon: Dove leaves small embroidered silk pieces at Moon’s threshold, and Moon leaves tea in return. She begs her husband to let her go out for the upcoming Moon Festival, but he refuses possessively. 

One day, Headman Yo and Three-Finger Lee visit the shop to stare at Dove, and she feels a strange pull toward Lee.

From September 15 to October 31, 1870, Petal survives life in the brothel and continues her plans to escape. During the Moon Festival, she’s given a traditional moon cake by a kind young client called Charley. Auntie Fong also gives the trafficked women moon cakes and takes them shopping to buy treats. At Old Man Sing’s shop, Petal sees Dove; although they can’t acknowledge one another, they exchange a meaningful glance. The women are returned to the brothel and are visited by men for sex. Auntie Fong asks Petal if she would be willing to have sex with a white man at the brothel. Petal agrees, hoping for a bigger tip than from the usual Chinese customers, but no white customer is presented. 

A while later, during a second excursion to Sing’s shop, Dove secretly passes Petal an embroidery of Petal’s home village. Headman Sam takes Petal to a saloon to meet the client white client Auntie Fong mentioned. He’s belligerent Frenchman named Michel Lachenais, who’s rumored to have killed three people. Petal goes to his room and has sex with him; he’s drunk and rough with her. Afterward, she gets into a wagon that she thinks belongs to Sam, but as the wagon carries her out of the city, she realizes that she has been kidnapped by Headman Yo.

After a whole day of traveling, Petal is locked in a shed for three days. She’s then led out by Headman Yo’s men, who beat and torture her until she falls unconscious. Back in the shed, she hears a commotion and is rescued by a police marshal, who arrests her and the men. The men are arrested for kidnapping, while she’s accused by Headman Sam of stealing $500, a ruse to have her captured and returned by the police. Petal is dropped off at the brothel. Auntie Fong persuades Sam to let Petal see a doctor, saying that she makes him good money, and Petal is taken to Dr. Gene Tong’s.

In 1926, Moon recalls the events of December 1870. She was shocked at Petal’s state when she was brought to her for medical treatment. Moon treated Petal kindly and told her a traditional story to give her hope and courage.

It is mid-December 1870, six weeks after Petal’s abduction by Headman Yo. She’s obliged to take more clients at the brothel, with the cost of her retrieval and treatment added to her contract debt. Undeterred, she secretly collects men’s clothing as an escape disguise. One evening, Headman Sam takes her to Higby’s saloon to see Lachenais again. As they arrive, policemen burst in and arrest Lachenais for the murder of his neighbor. On the walk back, Petal memorizes the streets, continuing to build a mental map for her escape.

At the victim’s funeral, a man incites the crowd to storm the jail. The sheriff tries to intervene, but a mob forms. Swept up in the chaos, Moon and Gene manage to slip away and decide to spend the night at their clinic for safety. That evening, they receive news that Lachenais has been removed from police custody and will be publicly lynched by the city’s self-appointed “Vigilance Committee.”

Continuing her 1926 recollection, Moon thinks back to the night after the murder. While she and Gene hid in the clinic, receiving news about the vigilantes’ plot to lynch Lachenais, she was consumed with anxiety. Gene tried to comfort her, but his words of love only deepened her fear that, at nearly 26, she would soon be considered old and discarded like “tea dregs” when she turned 30 if she couldn’t conceive a baby.

On December 17, 1870, Old Man Sing allows Dove to join him at the lynching of Michel Lachenais, eager for an opportunity to display his beautiful wife. Dressed in her finest clothes, Dove accompanies him to Poundcake Hill, where a large, festive crowd has gathered. From their vantage point, she sees many acquaintances, including Headman Sam, Headman Yo, and Three-Finger Lee. She also spots Moon and exchanges a silent, friendly wave. A mob brings Lachenais to a corral, where he’s hanged from a crossbeam. The drop is too short to break his neck, and he dies slowly. Afterward, the crowd disperses, and Sing takes Dove back to his shop.

On December 17, while the city is distracted by the lynching, Petal escapes in her disguise of men’s clothing. She walks for days, heading west toward the ocean. Her shoes fall apart, and she forages for food, feeling a sense of freedom. After reaching the coast near Santa Barbara, she’s discovered by Los Angeles police: A Chinese dormitory manager had reported her for a reward. She is again arrested on a fabricated charge of grand larceny. On the ride back, a firefight erupts in Los Angeles as Headman Yo’s men try to abduct her from the police wagon. In the confusion, the informer is shot and wounded before Petal is taken to jail.

On December 23, Dove is visiting Moon when Headman Sam bursts in with a severely beaten Petal, whom he leaves for Gene to treat. The two women clean Petal’s wounds. Petal tentatively engages with Moon’s suggestion that she marry a kind customer, mentioning Charley as a possible candidate, though the women conclude that a farm worker might suit her better. Moon then proposes a new plan: Bring Petal’s brother, Ah Loo, from China to help earn money to release her. Petal agrees, so Moon lends her the initial funds and writes a letter to her family, with Dove dictating the proper phrasing. Gene returns home with a gift for Moon: a white poodle puppy. Moon, who hoped that he was bringing her an adopted baby, masks her disappointment and names the dog Winter Melon. Dove notes that white is the color of death.

From December 23-31, Petal recovers at Moon’s apartment from her injuries, which include broken ribs and head trauma. Auntie Fong had persuaded Headman Sam to have Petal treated, and Gene argues that he and Moon should keep her for recovery. As she gets stronger, Moon and Petal devise a plan for Petal to grow medicinal herbs in tin cans on her high, inaccessible windowsill at the brothel. Once recovered, Petal returns to the Midnight Garden with seeds and soil. She asks her kind customer Charley—whose Chinese name is Ah Ming—to secretly bring her better soil and manure, and he agrees. The project gives Petal a new sense of purpose and potential freedom.