Paper Valentine by Brenna Yovanoff

Even before the murders, things have been wrong in Ludlow. The summer heat is stifling, a strange disease is killing the birds, and Hannah is being haunted by her dead best friend, Lillian.

These details -- the relentless sticky heat, the rotting heaps of feathers on front lawns and sidewalks, and Hannah’s matter-of-fact acceptance of Lillian’s ghost -- give Yovanoff's story the sensation of a dream where you are menaced in your everyday surroundings and can’t make your legs obey to run.

Goaded by Lillian, Hannah investigates the serial murders of young girls in Ludlow, becoming more obsessed as the victims begin to appear to her. Grief and closure are strong themes in this grisly mystery, but it is also about how people look at girls and their bodies, and how girls claim power. The killer arranges the bodies of his victims to represent innocence; Lillian’s death was caused by anorexia; Hannah chooses a romance with a strange and possibly dangerous boy.

As their circle of popular friends reorganizes itself, Hannah realizes that she and Lillian may have been mean girls at times, but she still taps into that power when another friend tries to tear her down. Now that Lillian is dead, what sort of person will Hannah be?

Too many books have a shallow fixation on romantic love, but the love between best friends is just as important.  The connection between Hannah and Lillian is what drives this story of loss and survival.