Sarah, portrayed by Olivia Wilde, and her husband Phil, played by Luke Wilson, are a young married couple living in New York City. Their lives take a dark turn when they take their 10-year-old son to a convenience store bathroom. While Phil steps a few feet away to grab juice from the freezer, he tries to talk to their son through the bathroom door but receives no response. To his shock, the gas clerk unlocks the door, revealing that the seemingly enclosed bathroom actually opens directly into the garage and outside, leaving the couple frantic as they search for their missing child.
Fast forward a year, Sarah and Phil find themselves at a party, clearly struggling to cope with the grief of losing their son, who remains missing. Phil mentions that Sarah has been prescribed lithium to manage her moods, while we witness her vacillating between hysterical laughter and deep sorrow. Tim, played by Giovanni Ribisi, Phil's brother, has become a self-proclaimed misfit, living on their couch while struggling with his own issues and providing little comfort to the grieving couple. His inability to remember their son's birthday only adds tension, culminating in Sarah admonishing him for his lack of empathy.
The film unfolds as we follow Sarah and Phil in their separate lives, each processing their child's loss in isolation and not supporting one another. Sarah, a middle school teacher, appears emotionally disconnected from her students. In a notable interaction, she notices Adam, a troubled boy portrayed by Ty Simpkins, who often throws tantrums and displays signs of autism. As she starts to connect with him, we see glimpses of her struggles as she aimlessly roams New York City, the purpose of her wandering leaving viewers uncertain whether she is seeking her son or lost in her grief.
Phil, on the other hand, serves as a uniformed NYC police officer. His day-to-day is marked by a haunting fixation on photos of his son. Phil frequently attends a support group where he bonds with Pete, played by John Leguizamo, whose own child was tragically killed. The pair discusses their overwhelming grief, with Phil remaining largely silent. When called to a domestic disturbance, the situation escalates dangerously, but Phil remains detached and uninterested in taking action.
As the couple continues to spiral, a detective uncovers a lead linked to a suspect with potential ties to their son's abduction, reigniting hope amid the torment. However, as time progresses, Sarah’s mental state deteriorates, pushing her towards reckless behavior. Deeply affected by the loss, she adopts a more juvenile appearance, dressing in hoodies and engaging in self-harm to numb her pain. Sarah’s interactions with Adam’s troubled home life become disturbing, as she begins to stalk Adam's family, leading to a heartbreaking moment of misguided affection when she engages in casual sex with Adam's father.
In her desperation, Sarah takes Adam under false pretenses, setting off an unsettling chain of events. As they drive away, Sarah is haunted by calls from Phil that reveal the tragic news regarding their son’s death, though Adam remains blissfully unaware. Stopping the car, Sarah's grief spills over as she cries out for her lost child. The story culminates in an emotional encounter with an elephant that captivates both Sarah and Adam, suggesting a glimmer of hope amid profound sorrow. The film closes with Sarah gazing into the eyes of the creature, leaving the audience contemplating the depths of her pain and the longing for connection as the screen fades to black.
