This supernatural thriller crackles to life with an eerie tension right from the start, but it gradually loses its urgency and devolves into silliness. On the morning of her 17th birthday, troubled it-girl Mary awakens naked, tucked into a bed in the display window of a Manhattan Crate and Barrel. Unable to remember what happened, she eventually convinces herself that her wild social life, replete with drinking and drug use, is to blame for the unfortunate predicament. Determined to carry on with the birthday revelry usually planned for her by her wealthy and privileged classmates at a Gossip Girl–styled private school, Mary endures a day of troubling visions and bizarre happenings, eventually discovering a horrific scheme involving her closest friends. The story is told in three parts. The first will draw readers in, but the second dashes the suspense with one overcomplicated revelation after another, all of them hinged on an unconvincing plot device in the form of an ancient Egyptian curse. Devoted urban fantasy fans might stick with it, but the near 400-page length won’t make this easy. (Supernatural fantasy. 14 & up)