Though her best friend Lillian died six months ago, Hannah cannot let go of the past, especially when Lillian's ghost is haunting her bedroom. Lillian wants Hannah to investigate a string of murders in their town, a string with victims connected only by a paper valentine, which has Hannah wondering if Lillian did not commit suicide after all. Meanwhile, Hannah knows she has no future with him, but still cannot take her mind off of Finny Boone, a larcenist and also, surprisingly, a boy with a streak of doing surprising acts of kindness.