Sullivan informs DA Doogan that Sal recanted his testimony, collapsing the case against Nicole. The Bainbridge family lawyer, Archibald Burns, arrives with Mrs. Bainbridge to demand Nicole’s immediate release. Doogan pivots his theory when Sullivan mentions Cassie’s connection to the Japanese workers at the Claremont, now suspecting that an espionage ring murdered Wilkinson. Doogan gets the entire police force in the region looking for Cassie.

Cassie and a Japanese woman named Yuko Sasaki are arrested in Healdsburg. A shop owner calls the police when she spots them, and she claims that she has previously seen them together, behaving “disgustingly, unnaturally.” Doogan holds a press conference announcing that a Japanese saboteur has been charged with Wilkinson’s murder. Isabella confronts Sullivan, condemning the new theory and criticizing his role in Japanese internment. Sullivan defends himself by saying that, unlike her, he lacks the wealth and social position to always act on his principles. He tells her that his own father was deported to Mexico in 1931, so he has been in a similar position to the Japanese American people. This only makes Isabella angrier, and she asks him if he changed his last name because he was ashamed of his heritage. Finally, Sullivan advises her to provide any alibi for Cassie and Yuko to Burns rather than Doogan.

At an emergency arraignment, Jessup, the witness from the hotel who previously claimed to see a Chinese sex worker outside Wilkinson’s room, now says that the woman was in fact Yuko. Next, Doogan presents evidence that one of the three Bainbridge girls was seen coming out of Wilkinson’s room. Afterward, hotel employee Adrianakis testifies that he saw Cassie and Nicole enter the Claremont through a back door at 11:15 pm, and manager George testifies that they walked out with Yuko. Doogan then calls Colonel Bendetsen, who is in charge of the Japanese internment program. Bendetsen testifies against Japanese Americans generally and claims that many of them are spies and can’t be trusted. 

However, the defense calls Dr. Margaret Chung, a prominent Chinese American physician, who is well loved by the defense personnel she treats and cares for. She provides an alibi for Cassie and Yuko. She testifies that she performed an emergency appendectomy on Yuko at the exact time of the murder, with both Cassie and Nicole present as witnesses. Doogan tries to undermine Dr. Chung’s testimony, painting her as a “deviant” who likes to dress in men’s clothes, but Judge Lewis Moss dismisses all charges against Cassie and Yuko.

Now that Nicole and Cassie have been cleared, Doogan immediately declares Isabella the new prime suspect. Sullivan interviews Isabella’s father, Roger Stafford, questioning him about why Wilkinson might have called his house on the night he was murdered. Stafford has no idea, but he says that Isabella is manipulative and cautions Sullivan against trusting her.

Sullivan then goes to the Stafford house to question Sadie. She tells Sullivan that she knew Wilkinson very well and that she might have been first lady if he became president. Soon after, she begins laughing uncontrollably and falls down, and when Isabella tries to help her, she throws a vase at her daughter. Before Sullivan leaves, Sadie warns him that Isabella flirts with men to manipulate them. 

At the Claremont, Sullivan speaks to the elevator operator, Pounds, who has been working at the hotel for many years. Sullivan asks him if Sadie had an affair with her psychiatrist, Dr. von Urban. Pounds says that this isn’t true—but Sadie had maintained a long-running affair with Wilkinson at the hotel. Her friend Tillie knew about it, and they arranged their tennis games at the hotel so that Sadie could meet Wilkinson there. Sadie was with Wilkinson when Iris died. Sullivan reports the affair to Doogan, theorizing that Wilkinson could be Iris’s biological father, providing Isabella with a revenge motive.

Sullivan learns that Miriam has been truant from school. He goes to her house to confront her and discovers that Rosemary hasn’t returned and that Miriam is alone at home. Miriam confesses that she has been working extra hours because her mother accumulated significant gambling debts. Miriam has been trapped in a fraudulent labor contract with her boss, Mickey, to help pay off her mother’s obligations.

A search warrant for the Bainbridge house is approved and executed. While searching Isabella’s room in her grandmother’s house, Sullivan discovers a card from Wilkinson asking her to meet him at his hotel room at midnight on the night of the murder. As Sullivan prepares to leave, Mrs. Bainbridge gives him a folder containing her written testimonial, claiming that it will reveal the true killer.

The narrative returns to Mrs. Bainbridge’s testimonial, which spans events from 1921 to March 1944. It reveals that Wilkinson was the biological father of Iris, the product of a long-running affair with Sadie that was facilitated by Dr. von Urban. Wilkinson made frequent trips to the Claremont, and he gradually became more interested in observing his daughter from a distance than in meeting Sadie. He was married and had a growing political career, and he became worried that his relationship with Sadie would compromise this. When he tried to break things off, Sadie begged him to come see their child, hoping that his affection for Iris would change his mind. Sadie told Iris that Wilkinson was her father, and this angered Wilkinson, who felt that Sadie was manipulating him. As they argued, they were negligent of Iris, who climbed into the laundry chute looking for a place to hide and then fell to her death.

Years later, after a lobotomy left Sadie mentally compromised, she developed an obsessive hatred for Wilkinson. The testimonial reveals that on the night of the murder, Sadie appeared at Mrs. Bainbridge’s house in an unwell state. She confessed to killing Wilkinson, claiming that God spoke to her and told her to do it. Mrs. Bainbridge states that she is revealing this information only because her granddaughters were wrongly accused.

Doogan dismisses Mrs. Bainbridge’s testimonial as a legal ploy, citing precedent that would make Sadie impossible to convict due to an “insanity” defense. He is dismissive of the idea that Sadie committed the murder, instead believing Isabella to be guilty. The note card that Sullivan found has gained them a warrant to search the Stafford house, and Doogan hopes that Sullivan will find the murder weapon there. 

As police officers are searching through the Stafford house, Sullivan confronts Isabella. He shows her the card that he found at her grandmother’s house, and she finally admits that she went to Wilkinson’s room on the night of the murder but found him already dead. She reveals that Wilkinson was her biological father in addition to Iris’s; Isabella found out about this only recently. He got in touch with her after seeing her at Madame Chiang’s party. She planned to meet him in his hotel room to receive a necklace from him as proof of paternity. In his room, she saw the necklace in the black jewelry box in his room—it was similar to the one Iris had—and she grabbed it before she left. Isabella admits that she lied to Sullivan before about Madame Chiang being involved in the murder. She says that she wanted to throw him off the scent because she knew that Sadie killed Wilkinson and she wanted to protect her.

A police officer interrupts to say that they haven’t found anything, but Sullivan tells them to keep looking. He then asks Isabella if Sadie has any hiding spots in the house, and she leads Sullivan to an attic balcony. Isabella finds the revolver there, but she handles the weapon before Sullivan can stop her, leaving her fingerprints on it. In the crime lab, Sullivan confirms that the gun is the murder weapon and lifts Isabella’s fingerprints from the surface. 

Believing that Isabella is innocent, Sullivan makes a decision to destroy the fingerprint evidence and wipe the gun clean. He lies to Doogan, stating that no usable prints were found on the weapon. After a neighbor confirms seeing Sadie out on the night of the murder, Doogan drops the case against Isabella.