Secluded Cabin Sleeps Six

On Christmas night 2017, the Maroni family gathers for dinner at the Florida home of Hannah's parents, Sophia and Leo. Hannah, the family peacemaker, manages the evening's tensions: Sophia is drunk and cutting, Leo smiles passively, and Hannah's brother Mako has fallen asleep after drinking too much. Hannah's husband, Bruce, a devoted but reserved tech professional, monitors their infant daughter, Gigi, while Mako's wife, Liza, endures Sophia's coldness. After dinner, Leo produces hidden gifts: Origins DNA testing kits, a consumer genetic testing service, for each family member. No one claims to have given them, and Liza throws hers away. Before leaving, Mako mentions a summer getaway at a secluded cabin in Georgia. That night, Hannah catches Bruce closing his laptop abruptly and notices a strange car parked outside, though she sets these worries aside.

Six months later, Hannah's suspicions about Bruce have deepened. He takes private calls and comes home late, and she discovers a cryptic message on his work phone from a contact named Angel. Bruce asks her to trust him but says he cannot explain due to classified work. They prepare uneasily for the cabin trip, leaving Gigi with Bruce's mother, Lou.

A mysterious narrator called Trina watches Hannah's house from the darkness. Trina has been hired as Mako's personal assistant at Red World, his gaming company, as part of a long-planned scheme. She texts a half brother to confirm she is "in" and calls this "the last one."

All six guests converge on the cabin: Hannah and Bruce; Mako and Liza; and Cricket, Hannah's lifelong best friend, with her new boyfriend, Joshua. Liza, experiencing migraines she attributes to in vitro fertilization treatments, receives threatening texts from an unknown number and blocks the sender without telling anyone. The cabin's owner, Bracken, warns about an approaching hurricane. At dinner, a hired cook tells the group that a man murdered his family on this property decades ago, and a sculpture made from a human skull and actual bones hangs over the dining table. When Hannah meets Joshua, she feels a disorienting sense of recognition she cannot explain. Upstairs, Mako confides to Liza that his Origins test shows he has no Italian ancestry, contradicting his father's supposed lineage.

Interspersed with the cabin scenes are flashbacks tracing the life of Henry, whose connection to the main plot emerges late in the novel. In 1997, Henry is a 13-year-old raised by Alice, a fearful mother who keeps them constantly moving. When Alice is murdered, a detective discovers that Henry's identity documents belong to a dead child and that Alice was living under a stolen identity. Over the years, Henry marries his childhood friend Piper and, through an Origins DNA test, discovers he has numerous half siblings fathered by the same anonymous sperm donor. He connects with one, a woman named Cat, who reveals that several of their siblings have died under suspicious circumstances.

At the cabin, the evening unravels. Bruce tells Hannah privately that he cannot keep working for Mako because of unspecified wrongdoing at Red World. Hannah and Cricket wander to a nearby lake and see a tall, motionless figure watching them from the trees. They flee. Liza, meanwhile, receives more threatening texts demanding she come to the guest cabin. She has been having a secret affair and is pregnant, uncertain of the father. Assuming her former lover is her stalker, she takes a small gun she stole from Mako weeks earlier and slips out alone. Instead of the man she expects, she finds Joshua and Trina. Trina reveals she sent the texts and, before Liza can react, stabs her in the abdomen. Trina stages Liza's disappearance with a forged note.

When Mako discovers the note and bloodstained sheets, the group panics. A lightning strike fells a tree, blocking the only road out. The power goes out. Hannah ventures outside and discovers the electrical line has been cut and the generator drained of fuel: deliberate sabotage. An unseen assailant strikes her on the back of the head, and she collapses.

Cricket, left alone with Joshua, watches his demeanor shift. He confesses he has not been honest, and Trina enters through the sliding door. Cricket learns Trina is Joshua's half sister and that their relationship was a ruse to get close to Mako's circle. When Trina strikes her across the face, Cricket grabs a kitchen knife and flees into the storm. She finds Hannah in the mud, and together they make their way to the guest cabin, where Mako cradles a barely alive Liza.

An extended flashback reveals a secret Hannah has carried for years. As a teenager, Mako rapes a classmate named Libby at a house party. Hannah, panicking, puts Libby in the shower, inadvertently destroying evidence, and drives her home. When Libby accuses Mako publicly, no one believes her. She never finishes school and eventually dies by suicide. Cricket, who helped that night, confronts Hannah about always protecting Mako.

As the group prepares to carry Liza to a car, Trina appears in the doorway holding the gun, Joshua behind her. She calls Hannah and Cricket enablers who cover for a monster, accusing Mako of rape, embezzlement, and money laundering. Hannah notices that Trina and Joshua share Mako's dark eyes and angular features and realizes with shock that they may all be biologically related through the same anonymous sperm donor.

A key flashback completes the picture. Cat meets Henry and reveals their biological father was Roy Alfaro, the "Miami Slayer," a serial rapist and killer convicted of murdering seven women in the 1980s while simultaneously donating sperm. Cat admits she has been killing the half siblings she deems dangerous, calling it Darwinism. Henry begs her to stop, but she walks away.

In the cabin standoff, Hannah tackles Trina during a thunderclap. The gun fires, grazing Hannah's arm. Bruce attacks Joshua. Cricket picks up the gun and shoots Trina, killing her. Joshua crawls to the body, sobbing Trina's real name: Cat. Moments later, agents from the Federal Bureau of Investigation (FBI) storm the cabin, and Mako is led away in handcuffs.

Bruce confesses the full truth: The FBI approached him before Christmas after discovering Red World was being used as a platform where predators groomed children, and that Mako was involved in money laundering and embezzlement. Bruce provided the FBI access to Mako's network; Angel was his handler. Henry, who has been trying to stop his half sister for months, arrives at dawn and explains that he, Catrina, Joshua, and Mako are all half siblings, children of the same serial killer who fathered them through sperm donation. Hannah also learns she was conceived via a different donor, meaning she and Mako are not biologically related. She cancels her Origins account: Leo is her father in every way that matters.

By Christmas 2018, Mako is under house arrest awaiting trial. Sophia and Leo, unable to forgive Bruce's role in Mako's arrest, are traveling abroad. Hannah and Cricket have visited Libby's mother to confess their part in covering up the rape, and they have written public accounts of what happened, receiving both condemnation and compassion. At Hannah and Bruce's new house, they set the table for a small gathering. Cricket arrives alone; Joshua vanished after the cabin and has not been heard from. Then Liza appears, pregnant with Mako's son, confirmed by DNA test. Bruce says grace, acknowledging that family is a choice, not a given. Despite everything, they gather and eat together, a fractured but chosen family.