In 1991, a formidable group of thieves orchestrates the theft of a rare $10 million diamond. This coveted gem had been securely deposited into a bank safe by an armored escort, which the gang targets after the escort leaves. They expertly access locker number 1798, making off with only the precious stone. With a skillful execution, they exit the bank in under two minutes, setting off an explosion in a van as a distraction while speeding away in their getaway cars.
As chaos ensues, two of the gang members betray their leader, Patrick Koster (played by Sean Bean), absconding with the gem. Fast forward to ten years later, just a day before Thanksgiving, where we meet the prominent Manhattan child psychiatrist, Dr. Nathan R. Conrad (portrayed by Michael Douglas). He receives an invitation from his friend and former colleague, Dr. Louis Sachs (portrayed by Oliver Platt), to assess a troubled young woman named Elisabeth Burrows (played by Brittany Murphy) at the Bridgeview Psychiatric Hospital.
Dr. Sachs reveals that Elisabeth, an 18-year-old who has never caused harm, has recently shown bouts of violence. With severe injury marks on her wrists and signs of heavy drug use, she presents a complex case. During their initial meeting, Elisabeth cryptically claims that Dr. Conrad desires what "they" wanted, leaving him confused about her meaning. She warns him that she won't disclose anything, prompting him to leave and return home.
Meanwhile, tragedy strikes as a woman in her twenties is discovered dead in the Hudson River. An autopsy uncovers that her neck was broken by human hands. Detective Sandra Cassidy (played by Jennifer Esposito) connects this murder to another man found lifeless just days earlier. As fate would have it, Patrick and the remaining gang members, recently released from prison, break into an apartment overlooking Nathan's. Here, they surveil Nathan's wife, Aggie Conrad (portrayed by Famke Janssen), who struggles with mobility due to an injury, and their daughter, Jessie (played by Skye McCole Bartusiak).
That fateful evening, Patrick kidnaps Nathan's daughter while Nathan is preoccupied with Aggie. The following morning, panic ensues as Nathan discovers Jessie's disappearance and realizes that his phone lines have been compromised, rendering him unable to contact the authorities. Patrick reveals that he has taken Jessie to force Nathan into extracting a six-digit code from Elisabeth's memory—an impossible task, as the kidnappers monitor Nathan's every move.
Determined to save his daughter, Nathan heads to the hospital and finds a burner phone, realizing that he must tread carefully. He breaks into Dr. Sachs' office, delving into Elisabeth's past, discovering her trauma stemming from witnessing her father's murder. Believing Elisabeth is feigning her symptoms to escape danger, he learns that she has been in and out of numerous hospitals over the years, indicating a brilliant mind capable of deceiving trained professionals.
Eventually, Nathan earns Elisabeth’s trust by revealing her daughter’s perilous situation. In a gripping twist, Dr. Sachs confides that the kidnappers also abducted his girlfriend, which culminates in her tragic death. Meanwhile, Aggie hears Jessie's voice and deduces the kidnapper's location, managing to fend off an attacker sent to eliminate her.
As Nathan secures Elisabeth's release from the sanatorium, she begins to recall vital memories from her past. It surfaces that her father was part of the very gang that stole the gem, betraying them and concealing it before his death. In a chilling revelation, the gang finds and murders him, leaving Elisabeth to escape with a doll that holds the hidden gem.
Realizing the code they need—the grave number of her father located on Hart Island—Elisabeth recalls placing her doll inside the coffin during the burial. In a daring gambit, Nathan and Elisabeth embark on a boat journey to Hart Island to recover the gem. Hot on their trail, the gang confronts them, leading Elisabeth to reveal the critical number, resulting in a frantic quest to unearth her father’s cry.
Under escalating tension, Patrick orders the grave to be excavated, but as he discovers the doll and the gem, his plans quickly unravel. Just as he intends to eliminate Nathan and Elisabeth, Detective Cassidy intervenes, leading to a brutal confrontation. Amidst the turmoil, Nathan seizes the gem and, in a desperate act, ensures Patrick is buried alive in the confrontation's chaos.
Finally, with the ordeal behind them, Nathan reunites with his wife and daughter, while it is implied that Elisabeth will find a new home with the Conrads, suggesting a glimmer of hope after the harrowing events.
