The second installment of the Stillhouse Lake thriller series picks up 12 days after Melvin Royal, a convicted serial killer, escapes from prison. His ex-wife, Gwen Proctor, formerly known as Gina Royal, hides with her two children, Lanny (nearly 15) and Connor (11), in a Knoxville motel. Gwen spent years as Melvin's unwitting cover, unaware he was torturing and murdering young women in their home garage. After his arrest, she changed her name and rebuilt her life at Stillhouse Lake, Tennessee, only to be targeted by Absalom, a shadowy hacker collective that previously helped Melvin manipulate and endanger her family. When she receives a threatening text from Absalom, Gwen decides to stop running and start hunting her ex-husband.
Gwen's closest ally is Sam Cade, the brother of Melvin's last known victim, Callie. Sam once stalked Gwen online, believing she was complicit in her husband's crimes, before concluding she was innocent. Despite their painful history, Sam agrees to help track Melvin. They leave the children with Javier Esparza, a retired marine who runs a gun range, and Kezia Claremont, a Norton police officer and Javier's partner, at Javier's fortified cabin near Stillhouse Lake.
Sam contacts FBI Agent Mike Lustig, a friend from his military service, who provides a lead: a woman named Arden Miller in the abandoned town of Markerville, Tennessee. Gwen and Sam find Arden, a transgender woman and former Absalom member, hiding in the ruins. She fled after discovering Absalom's blackmail scheme and threatening to expose their payment records; in response, Absalom tried to kill her by setting her apartment building on fire, killing seven people. Arden provides GPS coordinates for a cabin in rural Georgia belonging to a higher-ranking Absalom member.
At the Georgia cabin, Gwen and Sam recover receipts, printouts, and a hidden USB drive before discovering a concealed staircase leading to a locked steel door in the basement. Gwen senses a trap and insists they retreat. As they climb the stairs, the door opens remotely and triggers an explosion. Sam pulls Gwen from the wreckage; Lustig, who had been monitoring them nearby, is already on the scene when they regain consciousness.
Back at Javier's cabin, Connor harbors a secret. During his earlier abduction by Lancel Graham, a corrupt Norton police officer who worked with Melvin, Graham gave Connor a phone on Melvin's behalf. Connor has kept it hidden, rationalizing that surrendering the phone could lead to his father's capture and execution.
Gwen and Sam examine the USB drive, which contains video of a man being tortured and interrogated. The dying victim names "Rivard" as his employer. Lustig identifies the name as likely referring to Ballantine Rivard, a reclusive billionaire who founded the luxury retail chain Rivard Luxe. Among the paper receipts, Gwen notices bulk supplies shipped to a warehouse in Atlanta. At the warehouse, they find chains, dried blood, and the decomposed body of a private investigator named Rodney Sauer.
Gwen contacts Rivard directly and secures a meeting at Rivard Luxe tower in Atlanta. Rivard claims he hired Sauer to investigate Absalom after the group tormented his son, who died by suicide. He then shows Gwen and Sam a fabricated video depicting Gwen helping Melvin carry Sam's unconscious sister Callie into their old Wichita house. Though the video is a convincing fake, its effect is devastating: The fragile trust between Sam and Gwen fractures. Rivard offers to buy the video from the dark web in exchange for their delivering a sealed message to a man named Carl David Suffolk in Wichita, an Absalom contact Sauer had identified.
Rivard flies them to Wichita on his private jet. When confronted, Suffolk attacks Gwen, nearly strangling her before Sam intervenes. Lustig arrives with agents and takes Suffolk into custody. During interrogation, Suffolk reveals that Melvin filmed his crimes for Absalom's pay-per-view dark web marketplace. He then directs Lustig to a clip at the end of a seized video showing Gwen appearing to hand Melvin a knife during a murder. Lustig furiously confronts Gwen, and Sam walks out. Gwen is ejected from the FBI building.
Meanwhile, Connor begins texting Melvin from the secret phone. Melvin claims Gwen intercepted his letters over the years and insists he was framed for most of the murders. Their exchanges deepen Connor's bond with his father while widening his estrangement from his mother. Following Melvin's instructions, Connor downloads the fabricated video onto his regular phone and shares it. When Gwen returns to Javier's cabin, Lanny screams at her, Connor tells her to stop claiming innocence, and Javier and Kezia tell Gwen to leave. Only Detective Prester, a Norton PD detective whom Kezia has brought into the situation, urges caution, questioning the video's origins and who benefits from its release.
On the road with Sam, Gwen reaches her lowest point, proposing to offer herself as bait for Melvin. Sam restrains her from walking into traffic, telling her that having their mother killed by their father would devastate the children. Gwen agrees to keep fighting. That night, Absalom contacts Sam directly, offering Melvin's location in exchange for Gwen's motel address. Sam types "I'm in," planning with Lustig to use the arrangement as a trap.
Gwen is abducted from her motel room by a man in a rubber Melvin Royal mask who stuns her with a Taser and loads her into a white van. Sam and Lustig follow using a tracking device, but a crash delays them and the signal dies. The van has likely been loaded into a Rivard Luxe eighteen-wheeler.
Connor arranges to meet Melvin at the family's old Stillhouse Lake house, sneaking out with Boot, Javier's rottweiler. When he panics and tries to warn Melvin off, a stranger arrives in a white van instead. In the ensuing struggle, Lanny is grabbed, stunned, and dragged into the van, which speeds away. Lanny later kicks open the van's rear doors while the vehicle climbs a mountain road and escapes into the forest. She discovers a dilapidated cabin outfitted with cameras and a princess-pink canopy bed, a set used for filming Absalom's content, along with a pit of human bones outside. She contacts Kezia, who tells her the driver has been captured and police are coming.
Sam, rewatching the torture video, connects the Rivard Luxe truck to Gwen's disappearance and realizes Ballantine Rivard is not Absalom's victim but its leader. Rivard's son likely discovered his father's criminal empire and was murdered for it, his death staged as suicide. Sam and Lustig fly to Atlanta, flush Rivard from his tower with a fake anthrax scare, and capture him. Under pressure, Rivard reveals that a live pay-per-view event featuring Gwen's torture by Melvin is scheduled for midnight at a plantation outside Baton Rouge, Louisiana, with 1,000 virtual passes sold at $50,000 each. Lustig cannot secure FBI backup. He and Sam commandeer Rivard's jet and fly toward Baton Rouge.
Gwen wakes handcuffed to a bed in the decaying plantation house with Melvin beside her. He taunts her, revealing his communication with Connor and that Absalom operatives attempted to abduct Connor but captured Lanny instead. A woman named Annie, a drug-addicted helper working for Absalom at the plantation, drugs Gwen's water. In the torture room, a camera crew prepares to stream the event. Melvin forces Gwen to beg for the release of a young woman placed in a wire noose, then murders Annie in a savage frenzy when she mocks him.
Gwen drives a concealed splinter of floorboard into Melvin's eye. She fights her way upstairs, killing a guard and seizing his gun. When Melvin rises behind Sam with a knife, pretending his wound was fatal, Gwen takes Sam's gun and fires three bullets into Melvin's forehead. He takes three final breaths and dies.
One month later, Gwen and her family reclaim their Stillhouse Lake house. Lustig reports that Rivard's executive assistant cooperated, leading to nearly 1,000 arrests worldwide. Forensic analysis confirms both videos of Gwen were fabricated. Connor undergoes therapy for grief over his father. Lanny quietly dates Dahlia Brown, a friend from the community, and they wear matching braided bracelets. Sam's cabin lease expires, and Gwen invites him to move in. At the mailbox, Gwen finds a letter in Melvin's handwriting, mailed posthumously by an Absalom associate. She wraps it around a rock and throws it unopened into the lake, refusing to let him have the last word.