Annabelle Lee, a 17-year-old teenage girl from Miami, Florida, finds herself getting Marked just four years after her sister, Bianca. She is scared, infuriated, and sad, all at the same time. Getting Marked means that she has become a Fledling and has to leave her house, her family, her school, and her best friend in the whole world, David Castle, and move to the Miami House of Night, a vampyre finishing school. Being a Fledling is not fun: you will either die within a four-year period, or (with something more than luck) survive and become a Vampyre. To her luck, David promises her that, no matter what, he will never abandon her, and this changes her dull, crescent moon outline, to a beautiful filled-in triple moon: the two crescents on each side that face outward are blue and the full moon in the center is red. Great. She has to start her new life as a freak. But Belle is surprised to see that the people she meets are not scared or repulsed by her unusual Mark. With a little help from her new fledling and vampyre friends and David, she must find a way to survive in this new world.