15th Affair

The novel opens as Alison Muller, a blonde woman, crosses the lobby of San Francisco's Four Seasons Hotel. She proceeds to room 1420, where a man named Michael Chan opens the door. The two engage in a flirtatious role-play, pretending to be strangers. Before anything ordinary can interrupt, someone uses a stolen key card to enter the room, and three suppressed gunshots kill Chan instantly.

Sergeant Lindsay Boxer, the narrator and lead San Francisco Police Department (SFPD) Homicide detective, and her partner, Inspector Rich Conklin, are called to the scene. In room 1420, they find the unidentified victim shot three times, the room wiped clean of fingerprints. In the adjoining room, 1418, two more victims, a young Black man and a young white woman, are found dead alongside surveillance equipment. A fourth victim, housekeeper Maria Silva, is found in a supply closet, her key card stolen. Surveillance footage shows the blonde woman arriving at the hotel and a stealthy man in a bulky coat avoiding cameras. At 6:23 p.m., all footage cuts to static. That night, Lindsay's husband, Joe Molinari, does not answer her calls or come home.

The victim is identified as Michael Chan, 32, a Chinese history professor at Stanford University living in Palo Alto with his wife, Shirley, and two young children. Shirley watches the surveillance footage but does not recognize the blonde. Afterward, Lindsay reviews footage from an SFPD surveillance van near the Chan house and recognizes the driver of a passing black Mercedes as Joe. Conklin identifies the stealthy man from the hotel footage as Joe as well. Joe was present at both locations, despite having told Lindsay he was handling a security situation at the airport. Shaken, Lindsay initially withholds this discovery from her superiors.

Lindsay gives crime reporter Cindy Thomas, a member of the Women's Murder Club, a group of four professional women who collaborate on cases, photos of the unidentified blonde to publish. An anonymous tip identifies the woman as Alison Muller, 35, an executive at a Silicon Valley software company who has been reported missing. Her phone was last used near the Four Seasons.

Before Lindsay can follow up, Worldwide Airlines Flight 888 from Beijing crashes on approach to San Francisco International Airport, killing all four hundred-plus passengers. Claire Washburn, the chief medical examiner and Lindsay's best friend, discovers a second Michael Chan on the passenger manifest with the same Palo Alto address as the murdered hotel victim. The second body has been "misplaced" at Metropolitan Hospital amid the post-crash chaos.

Meanwhile, Muller, now disguised with streaked hair and brown contact lenses, enters the Chan home through the kitchen door and shoots Shirley in the forehead. When Lindsay and Conklin arrive for a follow-up interview, seven-year-old Brett Chan answers the door covered in his mother's blood. Five-year-old Haley describes a woman with "striped" hair but cannot identify Muller.

At Stanford, an assistant football coach reveals that Chan was in love with a woman named Alison. In Monterey, Muller's husband is unperturbed by her disappearance, but their 13-year-old daughter, Caroline, positively identifies the woman in the hotel footage as her mother.

Lindsay is repeatedly targeted by a group of Asian men who beat her outside her apartment and later ambush her near the Hall of Justice. An armed police raid on their Chinatown safe house kills all four attackers. Inside, Lindsay finds automatic rifles and a portable missile launcher of the type used to shoot down aircraft. A young waiter named Henry Yee, who sublet the apartment, reveals that the men needed to prove a certain person was aboard Flight 888. Yee glimpsed a burned body in one man's trunk, confirming the group stole the second Michael Chan's body from the hospital.

Seeking answers about Joe, Lindsay flies to Washington, DC. Joe's ex-girlfriend, June Freundorfer, a high-ranking Federal Bureau of Investigation (FBI) agent, reveals that Joe spent ten years in the Central Intelligence Agency (CIA) before joining the FBI and that he and Muller worked together. Muller specialized in honey traps, using seduction to extract intelligence, and Joe was her superior. June implies they were romantically close. A retired operative named John Carroll tells Lindsay that Muller loved Joe and warns Lindsay to prepare for divorce. Back home, Lindsay finds a hidden tablet showing Joe booked flights to Berlin with a second seat reserved under one of Muller's aliases.

Cindy's anonymous source, a young FBI surveillance tech, shows Lindsay hidden-camera footage from the hotel. One video captures the two operatives in room 1418 speaking to someone on their laptop. Lindsay hears Joe's voice ask if there has been any talk about "that plane from Beijing." Joe had foreknowledge of a possible threat days before Flight 888 was shot down.

Lindsay confronts Joe at a local CIA office, but he offers little explanation. He later contacts her, saying he has located Muller near Squamish, British Columbia. During the journey north, Joe tells his full story: The CIA asked him to return nine months earlier to run an operation involving Muller, who volunteered to work a honey trap on Chan, a suspected Chinese spy. Chan told Muller his father, a high-ranking Chinese intelligence official, planned to defect to the United States using false documents under his son's name. The father was aboard Flight 888. Chinese operatives in San Francisco, originally assigned to kill the defector upon arrival, instead shot down the entire aircraft with a missile. Joe says he was detained and interrogated by the CIA after the crash, preventing him from contacting Lindsay. He believes Muller became a double agent for the Chinese.

At a remote airfield in Pemberton, a firefight erupts as Muller and her associates attempt to board small bush planes. When Muller steps out to surrender, one of her Chinese associates fires at her. Her bodyguard throws himself in front of the bullet and is killed. Lindsay recognizes the bodyguard as Liam Dugan, the former Four Seasons head of security. Royal Canadian Mounted Police helicopters arrive and Joe handcuffs Muller.

Left alone with Muller in the car, Lindsay secretly records their conversation. She constructs a theory of the hotel murders: Dugan, seduced by Muller, shut down the hotel's Wi-Fi, killed the housekeeper, and shot Chan, while Muller killed the two operatives in the adjacent room. In exchange for Lindsay's promise to deliver messages to her daughters, Muller confesses to killing Shirley Chan to protect herself in case Chan had revealed her identity to his wife.

Muller is taken into CIA custody. An epilogue reveals she is held in an underground cell and interrogated daily for over a month. Joe visits once but says he cannot help. Her interrogator offers her a hot shower, and as she walks down the corridor, he shoots her in the back of the head.

In the final chapter, Lindsay hosts a dinner party with her friends. Joe appears at the door with roses. Lindsay stands in the doorway, uncertain whether to let him in. The novel ends without resolution, leaving Lindsay unsure whether to rebuild her marriage or walk away.