Theo Decker is an average 13-year-old living on the fringes of affluent society with his mother in New York City. His father abruptly left them the year before. His dad was an argumentative alcoholic; both Theo and his mother are happier without him. They have a close bond, but Theo is not perfect. As the novel opens, he and his mother are on the way to the prestigious private high school he attends to talk to the principal about his suspension for smoking on school property.
As Theo and his mother walk uptown to his school, they stop into a museum to wait out a sudden rainstorm. With only a short time before the meeting, his mother hurries to show Theo some of the important paintings. Theo is more intrigued by a girl he sees walking with an older gentleman. When his mother stops at her favorite painting, “The Goldfinch” by Fabritius, he listens to her explain the painter’s history and the picture’s significance.
But Theo is still entranced by the girl. So much so, that when his mother wants to run into another gallery, Theo tells her he is going to the gift shop, just so he can follow the girl and maybe speak to her. His mother hurries away, but Theo is near the girl and her guardian when a terrorist’s bomb explodes and the world fades to black.
When Theo wakes up, he is disorientated. The old man lies near him. In a daze, the man begs Theo to save “it.” Theo sees him point to “The Goldfinch.” The man seems panicked that “they” might steal it and put it in the customs house, so Theo hides the painting in a shopping bag. The old man then gives Theo a ring and tells him to go to Hobart and Blackwell and buzz the green bell. Theo pockets the ring and stays by the man until the man passes out.
Unable to find his mother in all the smoke and debris, Theo picks up the shopping bag and makes his way back to their apartment, as that is their emergency rendezvous. Overnight, social workers arrive and inform him that his mother was killed in the explosion. While they try to track down his father and grandparents, Theo is brought to the only friend whose address he can remember, Andy Barbour.
Andy and Theo had bonded for a time in elementary school when both boys had been outcasts and bullied. Theo had managed to recover from that time and been accepted by his peers in high school. Andy remained a social pariah. Andy and his parents welcome Theo into their home, but his younger siblings, Toddy and Kitsey, resent his intrusion.
Over the coming weeks, Theo walks through life in a cloud of grief, while the social workers try to find his father. He is also given medication from a psychiatrist, and from Mrs. Barbour, to help him sleep and cope with the anxiety caused by the bombing. The only emotion that breaks through his fog is that of fear when he thinks about the painting he left back at his old apartment. He knows he should turn it in to the authorities, but he worries about the repercussions.
Theo begins to wonder about the ring the old man had given him. After unsuccessfully trying to contact a shop with the name Hobert and Blackwell by phone, Andy advises him to try visiting the shop. Theo rings the green bell and is welcomed into the cluttered antique shop by James Hobert — Hobie to his friends.
Hobie takes the ring and tells Theo it was his business partner’s, Welty Blackwell, but the old man did not survive his injuries. Theo is allowed a brief visit with Pippa, the girl who had accompanied Welty to the museum. She had been Welty’s ward and niece. They had all lived together above the antique shop, and Hobie is helping Pippa recuperate from her injuries. She suffered a shattered leg, broken skull and brain injuries. Theo begins to visit the shop on a regular basis to speak with Hobie and Pippa. Hobie teaches Theo about restoration and antiques.
Theo is crushed when Pippa’s aunt moves her to Texas to continue her recuperation, but he continues to enjoy Hobie’s company. Hobie’s friendship and instruction is a balm to Theo’s soul, and his grief begins to lessen. But his world is turned upside down again when his father arrives unannounced at the Barbours’ apartment and insists on taking Theo to his home in Las Vegas. Theo returns to his old apartment with his father and his father’s new girlfriend, Xandra. As Xandra and his dad quickly decide what they can sell or use in Las Vegas, Theo secretly places “The Goldfinch” into a suitcase and jams it full of clothes.
Having never been out of New York City for more than a holiday, Las Vegas is like another world. His father and Xandra work odd hours and live in a large house in an empty neighborhood. Eventually, Theo makes friends with Boris, the son of a Russian businessman, who speaks several languages and has lived in many countries. The two are soon inseparable and spend their nights getting drunk, smoking pot and doing any kind of drugs they can get their hands on when they get money.
A year passes by without Theo noticing because of his constant drug use. His relationship with his father improves a bit, as his father no longer drinks, but he does take prescription painkillers. For a while, his father makes a lot of money at the casinos. He also does some sports betting.
When a man comes to the door and questions Theo about his dad, he knows things have taken a turn for the worse. In a drugged panic, Theo wraps “The Goldfinch” in paper and packing tape and hides it in his school locker, until his father assures him there is nothing to worry about.
Then one afternoon, his father asks Theo to call the lawyer in charge of his mother’s estate. He tells Theo he needs some money so he can send him to a private school. Theo hesitates, and his father hits him several times, demanding he cooperate. When the solicitor tells Theo that the money has to be sent directly to the school, his father breaks down in horrifying sobs. The following day, Theo’s father dies in an alcohol-related accident.
Still reeling from the effects of the LSD he and Boris did the night before, Theo becomes paranoid and desperate to return to New York before Xandra can call social services. Boris tries to get Theo to wait a day, but Theo refuses. While Xandra is passed out, they raid her bureau and discover a stash of cash and drugs. They split it, and Theo boards a bus bound for New York City. Desperate to find a place to stay, Theo shows up on Hobie’s doorstep, and the old man takes him in.
Over the next 10 years, Theo learns the ins and outs of the antique business and becomes Hobie’s business partner. Unbeknownst to Hobie, however, Theo sells several of Hobie’s hybrid restorations as original antiques. The ruse helps to get the shop out of debt. The money also helps pay for Theo’s prescription drug addiction. Although highly functioning, he cannot make it more than a few days without the numbing effect of some drug or another.
Trouble arises when a customer calls Theo out on a fake antique he bought. The man further suspects Theo has “The Goldfinch” and that he and Hobie have been using it to scam money, as the painting recently turned up in a foiled drug deal in Miami, but was lost again. As Theo has kept the painting hidden in a vault for years, he can believably deny the claim. Theo admits his fraudulent antique dealings to Hobie, who makes him promise to track down customers and repay them.
On top of this business crisis, Theo’s love life is in turmoil. Although in love with Pippa, she does not appear to love him, so he has become engaged to Andy’s sister, Kitsey Barbour. The match helps Mrs. Barbour get over her grief of losing Andy and her husband in a boating accident. As their engagement party draws near, Theo discovers that Kitsey is in another relationship with an old schoolmate Theo dislikes.
Theo takes a walk through the streets of the city, trying to clear his head, and is shocked to stumble across his old friend Boris. It is apparent that Boris now has a lot of money and is involved in some illegal activities. Theo is incredulous when Boris admits to having stolen “The Goldfinch” from Theo’s locker and having replaced it with a text book wrapped in the same paper and packing tape. It was he who used the painting in the Miami drug deal. Boris promises to help Theo get it back.
Boris sets up an intricate plan in Amsterdam and forces Theo to pretend to be a rich American art collector who wants to buy the painting. Once the painting is back in his hands, however, associates of Boris steal it back. A shootout ensues, and Boris is shot in the arm.
Theo and Boris each kill one of their assailants, and a third man gets away with the painting. Boris knows the young man who stole it and leaves Theo behind while he tries to get it back. Theo hides out in an Amsterdam hotel for a week, sick with fever and high on drugs, until Boris returns for him with a lot of money. Boris had decided to take Theo’s initial advice and call the authorities with the information he had about the painting’s whereabouts, and as the painting was recovered, they were given several million dollars as a reward.
Theo returns to New York and confesses everything to Hobie, expecting to be cast out forever. Instead, he and Hobie remain friends, and Theo spends the next year flying around the world, using the money to quietly buy back all the fake antiques he sold.