Zoey Montgomery is Marked by a vampyre Tracker after school at her high school one day. It's painful, and the new crescent-moon Mark on her forehead designates her as a vampyre-to-be. Her BFF, Kayla, and sorta-ex boyfriend Heath both freak out. Her mom and stepdad also freak out, and since Zoey's home life already stinks, she runs away. Oh—and the longer she resists going to the House of Night, where she will train to become a vampyre, the more likely her body will reject the Change and she'll die prematurely. No pressure or anything, though.
So Zoey drives to her grandma's house to seek guidance/comfort. Except she trips and falls and has a vision of the goddess Nyx, who is the deity of vampyres and who also has links with Zoey's ancestors, the Cherokee nation. Nyx tells Zoey that she has Marked her for a reason: to serve as Nyx's eyes and ears in the upcoming struggle. Then Zoey passes out.
Zoey wakes up in the House of Night, where her grandma brought her to be healed. She meets Nefret, the imposingly beautiful High Priestess. On her way to her dorm, Zoey is left alone for a moment and sees a girl trying to give a guy a blowjob, which he doesn't seem to want. This is weird and frightening, though the guy is really hot. When Nefret returns to guide Zoey to her dorm, she meets the girl: a blonde named Aphrodite who seems kind of haughty. Then Zoey meets her new roommate, a downhome Oklahoma girl named Stevie Rae.
At dinner, Stevie Rae introduces Zoey to the rest of their little group: Shaunee, Erin, and Damien. Also at dinner, Aphrodite shows up to invite Zoey to a Dark Daughters full moon ritual the next night (which is strange since Aphrodite seems to hate everyone in Zoey's new friend group).
As a vamp-in-training, Zoey sleeps during the day, and her classes start the next evening. She sees the hot guy from the hall, Erik Night. He seems to dig her. The rest of her classes are interesting, and Zoey does especially well in her equestrian studies class. The Full Moon Ritual for the whole school is new to Zoey, but the ceremony makes her feel good, and she thinks she can feel each of the five elements as they're invoked in the ritual.
Next Zoey goes to the dreaded Dark Daughters ritual. Aphrodite is snobby to her, but Zoey has an amazing time, especially when the goblet of mysterious delicious liquid is passed around. But when Aphrodite's minions inform Zoey that she just drank blood, Zoey runs outside to throw it up. Blood is gross… but it tasted so good.
Zoey is distracted by a meowing sound, and she finds a cute little orange kitty in a tree. She gets the cat down, then sees the figure of Elizabeth, a fellow student who just died. Huh? Kayla and Heath find Zoey sitting on the wall of the school, and they're generally obnoxious; Kayla clearly has a thing for Heath even though he claims to still be into Zoey. Zoey starts to hunger for his blood, but Kayla gets Heath out of there before Zoey can get more than a tiny lick.
Erik finds Zoey while she's upset about all this stuff, which is embarrassing, but at least he seems to be into her; he walks her to her dorm. Zoey tells Stevie Rae everything. The next night, Zoey feels confused about stuff, so she goes to Nefret for advice. Some instinct tells her not to tell Nefret about everything she's seen, so instead she calls her grandma, who advises Zoey to do the purification ritual of their people and pray to Nyx for guidance.
Zoey enlists her friends to help her do the purification ritual that night after classes. It works even though Zoey's a newb at ceremonial magic. There's more awkward flirtation with Erik, too, and though he says he's not with Aphrodite anymore, the fact that he was with her in the first place makes it hard for Zoey to trust him.
The next night in class, Elliott (a pudgy kid who no one likes) starts to cough up blood. Nefret has him rushed out to die with dignity—apparently this is what happens when a fledgling's body rejects the Change. Then Zoey goes to tell Nefret about the fact that Heath is obsessively texting her (maybe there's an Imprint going on, which is bad news). She sees Aphrodite having a vision, and rushes her into Nefret's office, but nothing Aphrodite says makes sense, so it's unclear how her supernatural affinity is doing any good.
Later, Zoey sees Elliott (even though he died). His eyes are red and he attacks her, but Nala fends him off. Then Zoey has to attend another Dark Daughters ritual, since she's decided to take Aphrodite (who leads the group) down a notch. Erik walks with her outside the school to a museum gazebo, where Aphrodite leads a ritual to honor the spirits of the dead since it's Samhain.
But Aphrodite messes up the ritual, and when Heath shows up to find Zoey, the spirits of the dead begin to escape the ritual circle, trying to snack on Heath. Yikes. Zoey's friends show up—she'd told them not to come, but they did anyway—and the five of them quickly create a new ritual circle to contain and banish the spirits. Aphrodite acts all uppity, but then Nefret appears and strips Aphrodite of her leadership of the Dark Daughters, instead giving it to Zoey. Ha.
Nefret heals Heath and erases his memory of the evening, and the kids head back to the school; Aphrodite tells Zoey off, saying that everyone is just being used. Then Erik joins Zoey and her friends, and Zoey feels like she finally belongs.