Mary Kubica, a New York Times best-selling author of psychological suspense, delivers another twisty domestic thriller with It’s Not Her (2026). Kubica is known for novels such as her 2014 debut, The Good Girl, and Local Woman Missing (2021), which often feature fractured timelines and intricate family secrets. It’s Not Her continues in this vein, opening with what should be a peaceful family vacation in the remote woods of Wisconsin. The retreat turns into a nightmare when Courtney Gray discovers her brother and sister-in-law brutally murdered in their lakeside cottage and their volatile teenage daughter, Reese, missing. As police swarm the resort, Courtney is forced to question everything she thought she knew about her family, exposing a web of secrets and lies that suggests the danger may have come from within.

The novel employs a remote setting and dual narrators to build suspense, echoing the real-life Keddie Cabin Murders of 1981, where a family was murdered in an isolated resort cabin. Like many of Kubica’s works, the narrative delves into the darkest corners of family life, exploring themes of The Destructive Potential of Family Power Dynamics, The Unreliability of Perception Under Trauma, and The Vulnerability of Children to Adult Misjudgments.The story unfolds through a nonlinear timeline, forcing readers to piece together the truth from fragmented memories and competing perspectives, a signature feature of the domestic thriller genre.

This guide refers to the 2026 Park Row Books edition.

Content Warning: The source material and guide feature depictions of graphic violence, physical and emotional abuse, death, child death, child sexual abuse, suicidal ideation, substance use, mental illness, sexual content, sexual violence, bullying, and cursing.

Plot Summary

Courtney Gray, on a lakeside vacation in Wisconsin, hears her 10-year-old niece, Mae, scream. Mae runs from her family’s cottage to Courtney’s, covered in blood and deeply distressed. Courtney leaves her own daughter, Cass, with Mae and goes to check on her brother, Nolan, and his wife, Emily. She finds their cottage door ajar. Inside, she discovers a bloody scene on the screened-in porch, where Emily’s mangled body lies. As she turns to flee, Cass and Mae appear in the doorway, having followed her. Cass screams at the sight of Nolan’s dead body at the top of the stairs, prompting Courtney to turn and see him for the first time. Courtney rushes the girls away. With no cell signal, they run to the resort’s main lodge for help.

Seven days earlier, Nolan and Emily’s 17-year-old daughter, Reese Crane, narrates the family’s tense arrival. Her parents fight about Nolan’s recent job loss and their strained finances. Miserable, Reese texts her friend, Skylar, that she wants to kill herself. At the cottage, she clashes with Emily over sleeping arrangements, ultimately claiming the screened-in porch for herself with Nolan’s permission, which further angers Emily. Reese then discovers on Instagram that Skylar is spending time with another friend, Gracie, making her feel jealous and abandoned. Her mood lifts only when she sees a handsome young man, Daniel, in the woods near the cottage.

In the present, Courtney and the girls reach the lodge, where the manager, Greta Dahl, calls the police. Detective Evans and his officers arrive. They have already been to the cottage and found Reese’s 14-year-old brother, Wyatt, asleep in his room. They bring him to the lodge, but Reese is missing. Detective Evans questions Courtney, who explains the tension in Nolan and Emily’s marriage. She also recalls Reese’s recent argument with Emily, in which Reese expressed a wish that her mother would die. This makes Courtney fear the police will view Reese as a suspect. Courtney’s husband, Elliott, returns from fishing and is devastated by the news.

Detective Evans questions the children. Wyatt claims he slept through the murders because Emily gave him a pink pill for his allergies, which he believes was Benadryl but is later revealed to have been Ambien. He remembers seeing his mother crying alone in the kitchen before he went to bed. Mae mentions that Reese had met a resort employee named Daniel. She describes him as having     a snake tattoo. Mae also overheard Reese crying one night, telling Daniel he was hurting and scaring her. Later that night, Wyatt wakes Courtney and shows her Reese’s location on Snapchat’s Snap Map. Though skeptical of the map’s reliability, Detective Evans agrees to investigate the location.

In a flashback, Reese meets Daniel in the woods, and they bond over their dysfunctional families. He asks her to meet him on the pier later. That night, Daniel takes her to a supposedly haunted cemetery. They smoke weed and kiss, unaware that Wyatt is secretly following and recording them. When Reese returns to the family cottage, Wyatt extorts money from her, saying that if she does not pay him, he will tell their parents about her sneaking out and use the recording as evidence    .

In the narrative present, a police search of the Snap Map location proves unsuccessful. During the search, Courtney meets volunteers Sam and Joanna Matthews, whose 11-year-old daughter, Kylie, disappeared five years earlier. Detective Evans informs Courtney that Emily and Nolan died from blunt force trauma inflicted by Wyatt’s baseball bat, which was found at the scene. He also reveals that Daniel Clarke is 24 and has been missing from work for two days.

Courtney’s fear and suspicion begin to turn toward her husband, Elliott. She finds what looks like blood on his fishing shoes, for which he gives conflicting explanations. On his iPad, she discovers a series of photos of Reese in a bikini. That night, Wyatt sleepwalks and violently slaps Courtney in his confusion, leaving a large bruise on her face.    

Flashbacks detail Reese’s brief, tumultuous relationship with Daniel. After seeing him flirt with another girl, Reese feels betrayed. That night, she wakes to find he has broken into the porch. He threatens to rape her at knifepoint. She manages to get the knife and stabs his hand, forcing him to flee. The next evening, after Reese harshly berates Mae and Cass for a cruel prank, she gets into a major argument with Emily over her behavior. Later, they reconcile, and Emily confides that she is unhappy and plans to ask Elliott for help filing for divorce.

Courtney’s investigation leads her to Daniel’s empty house, where she finds Reese’s bloody sweatshirt. Detective Evans discovers her there and reveals Daniel has a solid alibi, having left the state hours before the murders. Courtney finds a search for “Pearl Lake depth” on Elliott’s iPad. She also finds a post from Elliott’s Facebook account on the “Help Find Kylie Matthews” page, which claims Reese is the missing girl and gives their cottage number. Courtney realizes with horror that Cass and Mae made the post as a prank, not understanding the danger.

A final flashback from Reese’s perspective reveals the events of the murder. Sam Matthews, led to the cottage by the girls’ post and believing Reese is his daughter Kylie, forces his way inside. When Emily and Nolan try to protect Reese, Sam bludgeons them to death with Wyatt’s baseball bat and kidnaps Reese.

Detective Evans, alerted by Courtney’s discoveries, goes to the Matthews’ house and rescues Reese from a basement crawl space. Sam and Joanna are arrested. At the hospital, Reese tells the police she saw Greta Dahl leaving flowers on an unmarked grave in the cemetery. Under interrogation, Greta confesses she saw a man with a snake tattoo burying a body there five years ago. Believing it was Daniel burying Kylie, she helped cover the grave to protect him.

In the final chapter, Detective Evans’s perspective reveals the truth. Once friends with Daniel, he, too, has the snake tattoo.. Five years prior, he accidentally hit and killed Kylie Matthews with his car. He was the man Greta saw burying the body. He now plans to frame Daniel for Kylie’s murder, preserving his own identity as a good person.