Just as the title of the book implies, an unnamed boy sits down to interview the vampire. Well, he's just a vampire. We'll meet quite a few over the course of the book.
The interviewee, Louis, tells his interviewer about his early life—and early death—in Louisiana in 1791. On the night his brother dies, Louis is assaulted by a vampire who drinks his blood but does not kill him. The vampire later returns and transforms Louis into a vampire because he wants to take over his plantation, Pointe de Lac. It's like the worst episode of House Hunters ever.
Louis and this vampire, whose name is Lestat, live together on the plantation. Rumors spread among the slaves that the two men are supernatural creatures, and the slaves plan to kill them. Lestat and Louis burn down Pointe du Lac and flee to the nearby Freniere plantation. There, Babette Freniere, who has sort of a history with Louis, takes them in. But she, too, is suspicious, and she accuses Louis of being a devil. This is just the start of Louis's existential crisis. Is he or isn't he a demon?
Louis and Lestat take up residence in New Orleans. On one particularly desperate night, Louis feeds on a five-year-old girl and leaves her for dead. Later, Lestat finds the girl, Claudia, in a hospital. He pretends to be her father and brings her home to Louis, where he transforms her into a vampire.
Claudia never ages physically, but she grows mentally, soon becoming a woman trapped in a child's body. When Claudia realizes that she's trapped in this prison, she wants to know who made her like this. Louis admits that he killed her, but that Lestat made her a vampire.
Claudia decides that the best course of action would be to kill Lestat. No one likes him, anyway. She poisons two boys and tricks Lestat into feeding on them. Then she cuts his throat, and Louis dumps his shriveled body into a swamp.
Wanting to know more about the origins of the vampires, they decide to go to Europe. But first, Lestat returns from the dead and tries to kill them. Louis and Claudia burn down their suite (we're sensing a pattern here...) and leave Lestat for dead. For real this time.
Europe is like a classic vampire movie. People cower in inns adorned with crucifixes and strands of garlic, fearing an evil creature stalking the countryside. Louis and Claudia find the vampire, and this vampire is nothing like they are. It's more like a decaying corpse instead of a living, not-quite-breathing human.
Discouraged, Claudia and Louis move to Paris. One night, Louis is followed by a pair of vampires, and one of them invites him to the Théâtre des Vampires. Louis and Claudia attend a popular show in which a mortal woman is stripped and murdered on stage.
Claudia and Louis are taken backstage, where they meet Armand, a vampire who is human like they are. He is old, and he's more willing to share information than Lestat was. However, another member of the Théâtre, Santiago, is suspicious of Louis and Claudia, believing that they killed their maker.
Louis falls in love with Armand and, after much brooding, turns a doll-maker named Madeleine into a vampire to care for Claudia so that he can leave her for Armand. Unfortunately, Santiago has other plans. With a team of vampires, he drags Louis, Claudia, and Madeleine back to the Théâtre des Vampires. And who is there but Lestat. Back from the dead. Again.
Louis is restrained, and Claudia and Madeleine are given death by sunlight. Armand frees Louis, but he is furious at what these vampires have done. With a scythe and some gasoline, he sets the Théâtre des Vampires on fire (yes, definitely a pattern here) and kills any vampires who try to escape.
After the carnage is done, Louis and Armand return to America. Armand tells Louis that Lestat did not die in the fire. In fact, he happens to live back in New Orleans. Imagine that. Louis moves to New Orleans and eventually visits Lestat one last time. Lestat's a pathetic sight, and Louis ultimately feels sorry for him.
Armand then admits that he is the one who killed Claudia. He also admits that he thinks Louis is dead inside—he no longer possesses the drama and fire that used to drive him. Louis is like, "Yeah, pretty much," and Armand leaves him.
The end.
Well, that's the end of Louis's story. When he's done, the interviewer asks to be made a vampire. Louis thinks this is a terrible idea, so he bites him and leaves him for dead. But naturally, the interviewer doesn't die. When he wakes up, he goes through the tapes and finds a detailed description of where Lestat lives. The boy packs up and goes off to meet yet another vampire...
The end. For real.