Lucy and Ernessa have become inseparable. Ernessa's taken her over. She's consuming her.

What I saw wasn't real. And I know it wasn't a dream.

Ernessa is a vampire.

At an exclusive girls' boarding school, a sixteen-year-old girl records her most intimate thoughts in a diary. The object of her growing obsession is her roommate, Lucy Blake, and Lucy's friendship with their new and disturbing classmate. Ernessa is an enigmatic, moody presence with pale skin and hypnotic eyes.

Around her swirl dark rumors, suspicions, and secrets as well as a series of ominous disasters. As fear spreads through the school and Lucy isn't Lucy anymore, fantasy and reality mingle until what is true and what is dreamed bleed together into a waking nightmare that evokes with gothic menace the anxieties, lusts, and fears of adolescence. And at the center of the diary is the question that haunts all who read it: Is Ernessa really a vampire? Or has the narrator trapped herself in the fevered world of her own imagining?