Edmond Murray is a distressed father, portrayed by James McAvoy, who is summoned to the scene of his son Ethan's mysterious disappearance. There, he encounters his ex-wife, Joan, played by Claire Foy, and offers her brief comfort amidst the chaos. Determined to find his son, Edmond joins a search party while also undergoing questioning by the police.
Following the police interview, Edmond confronts Joan's new partner, Frank, who appears to have plans for a future without Ethan. Realizing that Frank has provided Joan with a Valium to help her rest, Edmond’s temper flares. In a fit of rage, he physically attacks Frank in the kitchen, leading to a moment of unconsciousness for Frank. In an effort to investigate further, Edmond contacts Inspector Roy, demanding that he look into Frank's potential involvement in Ethan's disappearance.
Though Edmond is arrested, no charges are pursued, as Frank chooses to forgive him, understanding the emotional weight he carries. However, Edmond's ongoing frustration leads him to meet with Inspector Roy again. In a clandestine moment, Roy cleverly hides Edmond's phone in a microwave to discuss sensitive matters, informing him that he has been removed from the case without any clear rationale.
Driven by desperation, Edmond illegally retrieves Frank’s phone and discovers distressing videos of Ethan from both recent weeks, revealing a mysterious car lurking in the background on multiple occasions. With help from Joan's brother, who works in insurance, Edmond locates the address tied to the vehicle.
Upon arriving at the site, Edmond conceals himself as he hears vehicle sounds approaching. Seizing an opportunity, he grabs a crowbar, incapacitates a man, and interrogates him aggressively using a blowtorch. Under duress, the man confesses that he distributes pictures of children to potential kidnappers, effectively facilitating the selection process for abducting victims. Armed with this critical information, Edmond races to a lodge where he believes his son is being held captive.
In a heart-pounding confrontation, Edmond manages to disable the captors' vehicle, takes out one of their accomplices, and reclaims his son, swiftly communicating his location to both Joan and Inspector Roy. However, tragedy strikes when Edmond is shot during their hasty escape, causing him to veer off the road. Joan and Ethan find temporary refuge behind a tree before being rescued by Roy.
The film concludes with a poignant scene set against the backdrop of nature, as Joan, Edmond, and Ethan stand together while Ethan practices with an RC quadcopter. Before departing, Roy reminds Edmond that the remorse and actions taken may factor into future court proceedings regarding the broader abduction network ultimately set to be dismantled. The bittersweet reality leaves the audience contemplating the lengths a parent will go for their child, encapsulated in a moving farewell.
