At an exclusive 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 her new and disturbing classmate. Ernessa is a mysterious, moody presence with pale skin and hypnotic eyes. Around her swirl dark rumours, suspicions and secrets as well as a series of ominous disasters.
As fear spreads through the school, what is true and what is dreamed bleed together into a waking nightmare of gothic menace, fuelled by the anxieties, lusts and fears of adolescence. At the centre of the diary is the question that haunts all who read it: Is Ernessa really a vampire? Or has the narrator trapped herself in her own fevered imagination?
