The Harvest by Richie Tankersley Cusick

NEW SCHOOL.
SAME ASSIGNMENT.
Something's wrong in Sunnydale, California...something more than the usual bad hair day. As long as there have been vampires, there has been the Slayer. One girl in all the world to find them where they gather and stop the spread of their evil and the swell of their numbers. In this generation, she is Buffy Summers, 16 years old and a new student at Sunnydale High. Her experiences at her last school persuaded Buffy to try to resume the life of a normal teenager. But it is no coincidence that Buffy has come to this town at this time. The area is a center of mystical energy, and all the signs point to an iminent, crucial upheaval. Once in a century comes The Harvest: a night when the Master Vampire can draw enough power to break free and open the portal between his world and ours...unleashing havoc. With the help of new friends and a new Watcher, Buffy's back in business....