A young boy named Theo finds himself deeply affected and in custody of the police following a devastating explosion at the Metropolitan Museum of Art in New York, which tragically claims the life of his mother. Guilt weighs heavily on him as he believes he is somehow responsible for her death. With his father nowhere to be found, Theo gives the authorities the name of a woman, Samantha Barbour, Nicole Kidman, who is a mother figure from his school. Reluctantly, she agrees to take him in, but Theo shows no outward signs of grief despite his emotional turmoil. As police question him about the details of the incident and his whereabouts, Samantha defends him, signaling her commitment to help him during this crisis.
Moving in with Samantha, Theo quickly befriends her son, Andy, who provides companionship amid the emotional chaos. The Barbour family, however, struggles with its own issues, particularly evident in the clashes between the authoritarian father and the rebellious oldest son, Platt [luke-kleintank]. The story takes a mysterious turn when Theo discovers he has taken a ring from a man killed in the explosion, which he is urged to return to Hobie [jeffrey-wright] at Hobart and Blackwell, an antique shop. Seizing the opportunity, he finds the shop's address and pays a visit, establishing a tender friendship with Hobie, who is grieving his lost partner, Welty.
Inhabiting a shared world of sorrow, Theo also connects with Pippa, Hobie's daughter, who is recovering from serious injuries sustained in the explosion. Although she is largely confined to her bed, their bond blossoms as they both mourn their families, losing their parental figures under tragic circumstances. Theo spends time between the Barbour household and Hobie's world, where he learns the intricacies of antique restoration and builds lasting relationships with the figures in his life.
However, Theo's reality shifts drastically when his estranged father, Larry [luke-wilson], and his new girlfriend Xandra [sarah-paulson] re-enter his life, demanding he leave New York for a barren neighborhood in the desert. Loneliness envelops him in this new environment until he meets another misfit, Boris [aneurin-barnard], who invites Theo into a reckless lifestyle marked by petty theft and substance use. As flashbacks reveal, Theo had been instructed by Welty to take a priceless painting, The Goldfinch, just before the tragic explosion, clinging to it as a source of comfort and remembrance of his mother.
Theo's struggles are exacerbated by his father’s financial woes, culminating in a fatal car accident driven by desperation. Learning of Larry's death during a drug trip, Theo decides to escape before he can be sent to foster care, returning once more to New York where he settles with Hobie. A significant time jump shows Theo maturing into a young man under Hobie's mentorship, yet his moral compass begins to blur as he involves himself in selling antiques, sometimes misleading customers about their authenticity.
As Theo navigates his new life, he faces challenges when a disgruntled buyer uncovers the truth about the painting he took, leading to a confrontation with Hobie, who feels betrayed by Theo's actions. The aftermath of continued tragedies strikes hard on him, especially with the deaths of Andy and his father, as well as his unrequited love for Pippa, who has chosen another man over him. Meanwhile, his romance with Kitsey, Mrs. Barbour's daughter, is marred by her own infidelity.
Amidst this swirl of despair, Theo's drug habits exacerbate his situation, bringing him back into Boris' life, who now leads a more prosperous existence. Boris divulges that he secretly took The Goldfinch from Theo years ago, swapping it out during a drug-fueled bender. Their journey to recover the painting unveils further chaos involving criminals and reckless endeavors gone awry, ultimately leading Theo into the depths of addiction. In a critical moment, Boris rescues Theo from a near-fatal overdose, providing them both with a glimmer of hope as he reveals that the police have retrieved the missing painting, restoring it to its esteemed place in the museum. The film leaves audiences pondering whether Theo can truly rise above the shadows of his past and reclaim a semblance of his lost life after the catastrophic events tied to the explosion.
