The Witch of Agnesi

When Peyton Newlin, a 13-year-old math genius disappears, math teacher Bonnie Pinkwater begins to investigate. One by one, Peyton's competitors turn up dead and Bonnie suspects the young math whiz may have something to do with it. But when Peyton also is murdered, Bonnie's sleuthing reveals a coven of witches, a violent skinhead, an abusive father, an amorous science teacher and a medieval mathematics manuscript that has been mistranslated.