Dr. Sophie Knowles loves using puzzles to make math fun for students. But when winter seizes Henley College, she must thaw out a cold case to track down a killer-her most difficult puzzle yet... Winter Intersession is in full swing, and campus is buzzing over the concert celebrating the bell tower’s reopening. The building has been shuttered for twenty-five years, and Sophie’s shocked to learn why-a student leapt from it to her death. But she’s even more troubled by the secrecy surrounding the case. After Sophie performs some quick calculations, she’s left with a nagging question: Was it really suicide? When one of Sophie’s favorite students, a performer in the concert, is brutally beaten and left in a coma, Sophie’s mind kicks into overdrive. The horrific incidents seem too coincidental to be unrelated, but can Sophie put together the pieces from a twenty-five-year-old murder before any other students get hurt?