The story begins with a catastrophic event: a terrorist bombing at the Metropolitan Museum of Art, which claims the life of Theo's mother. In the chaos that ensues, Theo impulsively takes a small, valuable painting called "The Goldfinch" and carries it away, setting in motion a series of events that shape his life.
Theo finds himself thrust into a world of uncertainty and loss. He is taken in by the wealthy Barbour family, where he befriends their younger son, Andy. As Theo navigates his new life, haunted by grief and guilt, he clings to the stolen painting as a connection to his mother.
The narrative follows Theo's tumultuous journey through various locations, including Las Vegas and New York City. He encounters a diverse cast of characters, most notably Boris, a Ukrainian immigrant and street-smart troublemaker who becomes Theo's closest friend. Together, they engage in risky behaviour, substance abuse, and petty crimes.
As the years pass, Theo's attachment to the painting grows, and he becomes entangled in a world of art forgery and underground dealings. He forms a unique bond with Hobie, a kind-hearted antiques dealer and restorer who becomes a mentor figure to him. Through his involvement in the art world, Theo gains insight into the value of art and the ways in which it can shape one's identity.
Throughout the novel, Theo grapples with themes of loss, grief, and the search for meaning in an unpredictable world. His experiences with love, friendship, and betrayal shape his understanding of morality and the consequences of his choices.
In the end, Theo confronts the truth about the painting and the implications of his actions. The novel raises profound questions about the nature of art, the complexities of human existence, and the transformative power of beauty.