Prophecies - Christopher Golden

Buffy has found it harder than she thought it would be to adjust to college life. The situation's not helped by the fact that Willow's adapted to UC Sunnydale like she was made for it. Buffy feels out of place, insecure -- and jealous of the ease with which Willow has fitted in. So when the spirit of dead Slayer Lucy Hanover warns Buffy in a dream of imminent disaster, the timing could hardly be worse.
Before long, a single moment of bad judgement catapults Buffy into a alternate future dimension where evil triumphs and vampires rule supreme. Imprisoned in the body of her 24-year-old self, she must uncover her past misstep and correct it -- otherwise she must face a truly terrible monster that she herself has created.
PROPHECIES is the first part of a novel in four installments, followed in consecutive months by DARK TIMES, KING OF THE DEAD and the climactic conclusion to the quartet, ORIGINAL SINS.