Telly Paretta, portrayed by Julianne Moore, is a grieving mother who lost her son in a tragic plane crash alongside ten other children heading to camp a year ago. In her struggle to cope, she frequently visits a psychiatrist, Dr. Jack Muncie, played by Gary Sinise. While Telly clings to her memories, her psychiatrist gently urges her to let go, causing her son's images to fade from her mind. Her husband, Jim Paretta, convincingly argues that this is a positive step, signaling her return to reality after a period of delusion. Dr. Muncie insists that her memories were merely fabrications stemming from a previous miscarriage and suggests she be admitted to a hospital for further care.
However, Telly remains adamant about her son's existence. Trying to uncover the truth, she visits Ash Correl, portrayed by Dominic West, believing he can validate her memories of her son, Sam, playing with his daughter, Lauren. In Ash's apartment, Telly discovers a child's painting hidden beneath his office wallpaper, leading to a realization that throws her into peril when Ash betrays her by contacting the police. Fortunately, NSA agent Carl Dayton, played by Robert Wisdom, intervenes before the situation escalates. As Ash begins to recover fragments of his own memories about his daughter, he decides to help Telly escape from the agents pursuing them.
The duo embarks on a chaotic journey, evading the NSA while delving into a dark world of potential alien abduction. Detective Ann Pope, played by Alfre Woodward, grows suspicious of the NSA's interest in missing children and collaborates with them to ensnare Telly. Turning to a secluded cabin, Telly and Ash confront a man named Al Petalis, acted by Lee Tergesen, who hints at the sinister nature of the agents tasked with keeping them in line. As the narrative escalates, their world shatters when armed agents disrupt their search for the truth.
Left behind is a haunting note on the cabin window, a plea from Telly and Ash that speaks to their children's abduction and their desperate need for assistance. As Telly recalls the name of the airline involved in the crash, Quest Air, she and Ash set out to investigate further, only to find an empty shell of a company shrouded in mystery. Their search leads them to confront the former CEO's house where they unearth shocking truths. During a tense encounter, Detective Ann discovers a man with peculiar healing abilities, ultimately leading her to a shocking realization about Telly's claims.
As the stakes rise, Telly and Ash find themselves on the run, tracing the mysterious man linked to the CEO's house. They confront him, leading to an unforeseen struggle that sends them both crashing out of a window and into the unknown. Telly's journey soon unveils deeper conspiracies as her psychiatrist reveals a dark connection to the alien searching for her son. In a heart-wrenching moment, Telly confronts the alien, begging for the return of her son while grappling with the painful realization that the experiment is designed to sever the bond between parent and child.
The alien manipulates Telly's memories, attempting to erase the essence of her son, Sam. In a climactic confrontation, she momentarily succumbs to the alien's influence, but the strength of her maternal love draws her back. Telly's unwavering spirit leads to a final showdown where she demands Sam's return, igniting a fierce determination within her. In an emotional twist, she ultimately finds her son in the park, reunited with Ash as they reclaim the normalcy of family life once more.
