Off the Deep End

The story opens with Jules Hart, a former marriage and family therapist, waking up submerged in freezing darkness after her SUV plunges through the ice of a frozen lake in Falcon Lake, Minnesota. Desperate to find her teenage son, Gabe, she grabs a hand in the murky water and drags the person to the surface, only to realize she has pulled out Isaac Greer, Gabe's basketball teammate. She dives back in but cannot reach the submerged car. Her body fails from hypothermia, and she surrenders to drowning, unwilling to let Gabe die alone.

The narrative splits into alternating timelines. One follows Jules, now a resident of Samaritan House, a court-ordered group home for adults with severe mental illness, as she is interviewed by Dr. Stephens, a young forensic psychologist. The other follows Amber Greer, Isaac's mother, during the investigation into her son's disappearance. Isaac vanished six days earlier while walking the family dog, Duke.

Amber is convinced Jules kidnapped Isaac. Her husband, Mark, believes Isaac was taken by the Dog Snatcher, a serial killer abducting and murdering adolescent boys across the Midwest. Two previous victims, Brady and Josh, disappeared months apart under identical circumstances: phones found on rural roads on day five, laundered clothes delivered at public parks on day eight, bodies discovered on day fourteen. A boy named Billy in a nearby town reportedly fought off the killer and provided the only eyewitness description. Isaac's disappearance mirrors this pattern exactly. Detective Hawkins, the lead investigator brought in from the Twin Cities, reveals that Isaac's phone has been wiped of all activity for three weeks, suggesting he had something to hide.

In her interview, Jules recounts that the two families lived three doors apart for seventeen years but were never close. She describes the night of the accident: exhausted after seeing eight clients, she was driving Isaac and Gabe home from a basketball game when she swerved to avoid a deer on a dark, icy road. The car plunged into the frozen lake. Isaac survived and dove back in when Jules failed to resurface, pulling her out and performing CPR, breaking one of her ribs. Jules woke in the hospital to learn Gabe had not survived.

Jules's grief consumed her. She abandoned her therapy practice, began living out of her car, and eventually parked on railroad tracks. She survived being struck by a train and was placed in a locked psychiatric unit before transferring to Samaritan House. Meanwhile, Amber recounts Isaac's severe deterioration: He curled in the fetal position clutching stuffed animals, sobbed that it should have been him who died, withdrew from all friends, and quit therapy. His grief counselor, Theresa, called it the worst case of survivor guilt she had ever seen. Amber was puzzled by this intensity because Gabe had often been unkind to Isaac, and the two were never close.

Jules reveals that Isaac initiated their relationship. While she was hospitalized, he appeared in her doorway, furious she had tried to kill herself after he saved her life. Their shared near-death experience created an intense bond. Isaac smuggled himself onto her visitor list by posing as her cousin and visited regularly throughout her stay. Jules describes the connection as transcending ordinary relationships and insists it was never sexual.

When Isaac broke off contact at his parents' urging, Jules's behavior escalated. She called fifty-two times in one hour, showed up at the Greers' house and punched through the glass door when Amber refused to open it, appeared at Isaac's school, and mailed him a knot of her hair as a symbolic gesture. The Greers filed a restraining order. One week later, Isaac disappeared.

On day eight, Isaac's clothes are found in a sealed box at a local park, matching the Dog Snatcher's pattern, but the delivery occurred while Jules was in a recorded session with Dr. Stephens, eliminating her. Amber drives to Samaritan House, slips inside using a fake name, and confronts Jules, pleading mother to mother. Jules responds with a look of pity and satisfaction; Amber shoves her and is pulled away by staff. Detective Hawkins reprimands Amber, revealing the team had been carefully building Jules's trust, which the outburst may have jeopardized.

A critical break comes when Hawkins discovers that Isaac's clothes were not laundered with the same detergent used in the previous Dog Snatcher cases, suggesting a copycat. He asks to collect a sample of the Greers' specialized detergent, purchased for their younger daughter Katie's eczema. Mark snatches the consent form before Amber can sign it. Then Billy confesses he fabricated his entire encounter with the Dog Snatcher to impress his mother after their difficult divorce, meaning the only eyewitness profile was fiction.

That night, Amber watches Mark pour their detergent down the drain, followed by bleach. The next day, with faucets running to mask their conversation from potential surveillance, Mark confesses. He secretly created an account called Loserstreet41 on Dracho, a violent online role-playing game, to monitor Isaac's activity. He discovered Isaac had built a server where players earned points by killing students at a virtual school modeled on Falcon Lake High. The violence bled into reality, with players vandalizing bullies' property and posting evidence. Isaac, worshipped as the server's lord, invented stories of his own revenge acts. Mark never told anyone, believing he could steer things from within. He destroyed the detergent after Hawkins's revelation suggested Isaac might be involved in his own disappearance.

Amber confesses in return: Weeks earlier, Isaac overdosed on his antidepressant medication. She kept it from Mark because Isaac seemed frightened by what he had done and soon showed improvement, cutting off contact with Jules and befriending a boy named Allen. They discover Isaac's computer has been wiped clean and realize the staged kidnapping was designed to divert law enforcement to rural areas, leaving the school vulnerable for a coordinated attack.

On day fourteen, news breaks of an active shooter at Falcon Lake High School, and a student identifies the shooter as Isaac. Amber and Mark escape through a basement window and sprint to the spot on the lake where Gabe drowned. They find Isaac at the water's edge in a blood-spattered jacket, gun in hand, with Jules beside him. Isaac reveals the truth about the accident: Jules made him and Gabe switch seats because she feared Isaac would get carsick. Gabe forgot to buckle his seatbelt in the back and was thrown from the car on impact, dragged fifty feet under the ice. Isaac declares that death has attached itself to him and will not relent until he gives it what it wants. He raises the gun under his chin.

Mark reveals he is Loserstreet41, Isaac's anonymous closest companion on the Dracho server. Isaac is stunned. Jules tries to intervene, professing her love, but Isaac turns on her with contempt, calling her delusional and revealing she is pregnant with his child. He briefly aims the gun at Jules, but Mark steps between them. With sirens approaching, Isaac, weeping, hands the gun to his father.

Three months later, Isaac awaits trial at Bridges Academy, an acute psychiatric facility. He is charged as an adult with first-degree murder: Two of the boys he shot died. Allen, who met Isaac through Dracho, provided his grandmother's basement as a hiding place and served as co-conspirator. Isaac's shooting was the signal for coordinated attacks by other boys from the server; Allen and two others died during their rampages, while Isaac was again the sole survivor. Katie, Isaac's younger sister, refuses all contact with him, calling him a murderer. Mark and Amber have grown closer through the ordeal.

In the final chapter, Jules, in jail after pleading guilty to sexual abuse charges, tells Dr. Stephens she and Isaac conceived the child through artificial insemination, arranged by sneaking Isaac into Samaritan House with the help of a compliant overnight staff member. She explains the pregnancy was their shared reason to stay alive and insists she had no knowledge of the shooting, claiming she raced to the lake to prevent Isaac's suicide. Throughout the visit, Jules exhibits no remorse: She rubs her stomach with pride, flirts with Dr. Stephens, and muses about second chances at love, her delusions fully intact.