Buffy the Vampire Slayer: Prophecies (The Lost Slayer, #1)

Buffy Summers' adjustment to life at U.C. Sunnydale has not gone smoothly. She feels awkward, insecure, and a bit jealous that Willow's all over the college life. So when the spirit of deceased Slayer Lucy Hanover appears to Buffy in a dream with news of impending danger, the timing couldn't be worse. Besides, there's plenty of evil afoot as it is. A unified troop of vampires has descended upon Sunnydale, operating with a cohesion unusual to most bloodsuckers. Giles thinks a spell will help the gang combat these foes, but tension between Buffy and Willow gets in the way of demon hunting.

Before long, a single moment of bad judgment catapults Buffy into an alternate future dimension where vampires reign supreme. Imprisoned in the body of her 24-tear-old self, the Slayer must uncover her past misstep and correct it -- or risk facing a terrifying monster that she herself has created...