The main character is Tarquin "Quinn" Blackwood, a child of the Blackwood clan, which is a powerful and old family in New Orleans. Tarquin is haunted by a mysterious spirit named Goblin, who is attached to him spiritually. He realizes that he is unable to defeat this creature alone. Risking his life, Quinn embarks upon a quest to enlist the help of the vampire Lestat de Lioncourt. Lestat, after a fashion, agrees to help Quinn.
The novel develops as Tarquin recounts tales of his growing up, his youth, his family, and even his forced conversion and acceptance of the Dark Gift by the hermaphrodite Petronia. His stories allow Lestat to better understand the reach and power of Goblin, who continues to haunt Tarquin. Lestat also discovers that Tarquin is connected to the Mayfair clan of witches, which also makes New Orleans its home. This information, combined with his failure to defeat Goblin, forces Lestat to request aid from Merrick. Merrick, a powerful Mayfair witch-turned-vampire, agrees to help.
It is revealed that the now-bloodthirsty Goblin, who looks exactly like Tarquin, is in fact a baby boy's spirit—the spirit of Tarquin's twin brother, who died only days after being born. The child did not leave this world; he is bound to Tarquin and is relentlessly jealous to experience what Tarquin does.
Merrick fashions a ritual, using the corpse of the dead twin, to exorcise Goblin. During the ceremony, Merrick joins herself with the flame and the corpse. She carries her spirit and that of the child to the Light and perishes. Lestat is bereft of Merrick, whom he adored; but he now has Quinn, a new vampire to cherish.