The Goldfinch is a tale of loss, survival, and the twists of fate. Thirteen-year-old New Yorker Theo Decker sets out one fateful day with his mother to meet with school officials after having been suspended from school. But, when he and his mother take shelter from heavy rain in the Metropolitan Museum of Art, a terrorist sets off a bomb that kills his mother. The disorientated and terrified boy is given an puzzling message and a ring by an old man named "Welty" Blackwell who is dying. Because the elderly man has pointed at a painting of a small, pretty goldfinch, in his panic Theo steals it before fleeing the wreckage.
As it turns out, the captivating painting of the goldfinch becomes representative of his mother for the lonely Theo, who clings to it after his father abandons him. Theo is taken in by the Barbour family and, as narrator, describes his feelings:
“I had fallen off the map....The disorientation of being in the wrong apartment, with the wrong family, . . . groggy and punch-drunk, weepy almost. . . . I kept thinking I’ve got to go home and then, for the millionth time, I can’t.”
While living with the Barbours, Theo encounters again a girl named Pippa who was with the old "Welty" on the day of the bombing. Pippa appears and re-appears at intervals in the narrative, almost as a harbinger of danger. Another person that Theo meets is a man named James Hobart ("Hobie"), who restores furnitue.
Unfortunately, Theo's father, Larry Decker, re-enters the narrative and whisks his son away from the Barbours, taking him and his addict girlfriend Xandra to Las Vegas. There, the unsupervised Theo makes friends with Boris Pavlikovsky, and the boys eat pizza, and watch television for countless hours as they bond. They also engage in dope smoking and petty thievery while his father gambles and Xandra snorts cocaine. But, this life comes to an end when Mr. Decker goes into debt with the crime syndicate from gambling. He asks Theo to call an attorney and ask him to release funds, but Mr. Bracegirdle senses that something is not right and refuses. Theo's father then flees Las Vegas, but dies in a car crash. Greatly disturbed by this loss, Theo wants to return to New York; Boris, however, will not accompany him.
Hungry and desolate in New York because Mr. Barbour shuns him, Theo reaches Hobie's shop where Pippa is also there, welcoming him. Eight years later, Theo becomes a full partner in Hobart's shop. However, in order to save Hobie from bankruptcy, Theo sells fake antiques and one of the purchasers attempts blackmail in retaliation. To complicate things further, Boris appears, confessing that he actually stole the real painting of the goldfinch years ago. Because he feels that Theo should own the real one, he relates his plan to fly to Amsterdam and retrieve it from the men who hold it. When he does so, accompanied by his "heavies," there is a shoot out and Boris is hit in the arm, but Theo fires at the would-be killer and saves him. Amazingly, Boris and Theo succeed in attaining a reward because they are able to tell the "art recovery police" where several valuable paintings are located.
Critic Woody Brown writes that Theo's life has "a poetic trajectory" because despite all his turns of misfortune, the boy returns to the painting of the goldfinch that, for him, is symbolic of his mother. “The painting,” he observes at the novel's end, “was the still point where it all hinged: dreams and signs, past and future, luck and fate.”