Game On: Tempting Twenty-Eight (stephanie Plum, #28)

Stephanie Plum, a bail bonds enforcement agent in Trenton, New Jersey, wakes at 2:00 a.m. to find an intruder in her apartment. She recognizes Diesel, a physically imposing man with unexplained talents who works a mysterious international job and surfaces in her life every few years. He is searching for Oswald Wednesday, a fugitive hacking into a system belonging to Diesel's unnamed employer. Stephanie is also looking for Oswald: He skipped his court date after being arrested for breaking into a cop's townhouse. Diesel describes Oswald as a graduate of the Massachusetts Institute of Technology (MIT) who holds artificial intelligence patents and enjoys inflicting pain, with ties to several disappearances. Stephanie agrees to cooperate but insists on making the formal capture herself to collect her recovery fee.

At the bail bonds office, Stephanie's coworker Lula, a brash former sex worker who serves as her self-appointed partner, and office manager Connie Rosolli brief Stephanie on new cases. Stephanie and Lula confirm that Oswald's listed rental on Dugan Street is a fake address. At a Porsche dealership, they learn Oswald recently serviced a black 911 Turbo S. Connie directs them to Melvin Schwartz, a twenty-six-year-old local hacker who reveals that his online group, Baked Potato, briefly penetrated Oswald's private network before being locked out. Diesel persuades Melvin to help them track Oswald. They follow Melvin to Clark Stupin, another Baked Potato member, but find no trace of Oswald.

Friday evening, during dinner at Stephanie's parents' house in the Burg, a tight-knit community on the edge of Trenton, her boyfriend Joe Morelli, a plainclothes police detective, receives a call about a homicide. Clark lies dead with his hands bound, his throat cut, and his tongue severed beside his body. Diesel arrives, and they rush to check on Melvin, who has vanished from his loft. Melvin later turns up at Stephanie's apartment in a panic: He received a message from Oswald reading "Retribution" and found Clark dead. Over the next few days, Stephanie shuttles Melvin between safe locations, including Lula's home, a park tent, and her own apartment.

Saturday, Stephanie and Diesel attend a car show hoping to spot Oswald. He taunts them via text, claiming to be in plain sight, then escapes. They later chase his Porsche, but he evades them by driving the wrong way on a divided highway. Sunday brings a second murder with the same signature: A man in Hamilton Township is found dead with part of his tongue cut out. Stephanie secretly takes the victim's laptop from the crime scene before police forensics arrives. Melvin accesses the laptop and identifies the victim as Mushy2, a fellow Baked Potato member. That night, Diesel's cousin Wulf, whose full name is Gerewulf Grimoire, appears in Stephanie's bedroom in a flash of light, announcing that "Auntie," the mysterious employer Diesel and Wulf share, sends her regards. Diesel explains that Wulf has been sent for the endgame of the Oswald operation.

Monday, Stephanie's father, a part-time cab driver who has unknowingly been picking up Oswald from the downtown area, calls to report dropping Oswald at the train station. Stephanie confronts Oswald on the platform, but he pepper-sprays her and shoves her onto the tracks. Diesel grabs her seconds before the train arrives. The rescue goes viral, earning Diesel the nickname "Hero Hottie." That evening, Oswald torches Diesel's motor home and calls to warn that a larger threat is coming. Diesel moves into Stephanie's apartment.

Morelli reports that a national query has turned up three additional murders matching Oswald's tongue-mutilation method. Stephanie and Lula spot a young woman knocking on Melvin's door and identify her as Charlotte Huck, a twenty-five-year-old MIT graduate and Trenton High School alumna. A key revelation emerges: Charlotte's townhouse at 108 Spruce Street sits next door to 106 Spruce, the cop's house Oswald broke into. His arrest was a mistake; he was targeting Charlotte's house. Charlotte, who has been living in her car since recognizing Oswald during his arrest, confirms she is Charley Q, the fourth Trenton-based Baked Potato member. Stephanie introduces Charlotte to Melvin, and the two share an instant connection rooted in shared intellectual passions and mutual shyness. Their budding romance becomes a quiet thread throughout the story.

The danger escalates when Oswald ambushes Stephanie and Lula outside Charlotte's townhouse, shooting Lula twice in the leg. Stephanie wrestles the gun away and shoots Oswald in the arm, but he escapes. She moves Melvin and Charlotte into Rangeman, the high-tech security firm run by Ranger, a security expert with whom Stephanie shares an unconventional bond. Ranger provides private rooms and round-the-clock protection in the firm's seven-story downtown building.

Thursday, Oswald cuts power to half of Trenton and issues an ultimatum: Hand over the last two Baked Potato members by midnight Friday, or he will shut down the grid indefinitely. Over the following days, Oswald destroys Stephanie's car with a bomb, and a replacement vehicle is shot up by a street gang. Diesel traces Oswald's movements through Uber records and upscale food stores, narrowing his location to the State Street area downtown.

Friday, as Stephanie returns to her car, Oswald ambushes her. He has strapped an explosive vest to the sleeping Lula and holds a remote detonator. At gunpoint, he forces them to his hideout in a vacant condo building. Oswald reveals his full plan: He hacked into the Russian sector of the International Space Station and installed software to control its propulsion systems, intending to ransom participating nations for 100 million dollars each while threatening to crash the station into a major city. He planned to crash it regardless, targeting the Goddard Space Flight Center, a National Aeronautics and Space Administration facility, as revenge for being fired and blacklisted. The Baked Potato group's hack disrupted this scheme when one member installed ransomware that locked Oswald out of his own system. He has been killing members to discover who did it. Oswald contacts Diesel and demands Charley Q and HotWiz, Melvin's hacker alias, in exchange for Stephanie and Lula, threatening to cut off Stephanie's fingers starting at midnight.

Melvin and Charlotte escape Rangeman after Charlotte hacks the building's security system. They trace food delivery records to Oswald's building and climb to the roof of an adjacent condemned building with store-bought rope and improvised harnesses. Melvin rappels to the bedroom window while Charlotte monitors his camera feed from the roof. When Oswald bursts in, Melvin swings through the glass feetfirst. As Oswald aims at Melvin, Charlotte slides down the second rope wielding a .44 Magnum she took from Rangeman's gun range and shoots Oswald in the chest, killing him instantly.

Ranger's team arrives moments later, having tracked the pair via drone. His explosives expert defuses Lula's vest. Wulf appears, and a helicopter sent by Auntie hoists Oswald's body away, eliminating public exposure of the space station hack. Diesel whispers "next time" to Stephanie and departs. Ranger brings Stephanie to his apartment for wine and food; she declines to stay, acknowledging the pull of her relationship with Morelli.

Saturday evening, Morelli arrives for their postponed date night. He mentions that intelligence reports indicate Oswald has "left the country," a diplomatic fiction they both accept. Stephanie presents a chocolate cake she baked from scratch, and Morelli declares he is in love. The novel closes with the couple at ease, the crisis behind them.