Petrified

Four high school seniors keep the pact they made six years earlier by reuniting in the town they all moved away from. The friends are hoping that Karin Potter, a shy outcast once included in their group, will join them, until Mrs. Potter, Karin's strange, embittered mother, tells them that her daughter has committed suicide. The four are devastated by the news, yet are soon faced with a more immediate concern: after breaking into the now-abandoned Waxhouse, a favorite childhood hangout, they must escape from a maniac who is lurking in the building and has sealed its exits. A grisly murder is followed by a near-fatality as Locke ( Kill the Teacher's Pet ) depicts the madness of the criminally insane. Unfortunately, little happens until the novel's midpoint, and except for the impulsive Bret, there's not much character delineation among the friends. The resolution also sidesteps credibility (an alive, albeit weakened, Karin breaks down a padlocked door), but horror story aficionados may forgive these shortcomings. Ages 12-up. (Feb.)