After the murder of a teenage girl in a suburban neighborhood, retired FBI Agent Karen Ellison is recruited by the local police chief to help solve the case. Karen is reluctant, haunted by a botched FBI investigation from her past that led to a killer being set free to murder again. Blaming herself, the guilt forced Karen into retirement - but this time her own teenage daughter goes to the same high school as the victim, so she reluctantly agrees to aid in the investigation. She is paired with Simon Jury, a wide- eyed inexperienced detective and the two are quickly convinced Dobson, a local sex offender is their prime suspect. He has the predatory past, the motive, and even the dead girl's necklace in his possession. But when Dobson is exonerated, Karen and Jury have to dig deeper. Suspicion runs rampant as the real killer begins toying with Karen. Could it be Jury with his hidden violent past? Or one of the two boyfriends the victim was secretly dating? Or someone else in plain sight? Who is the killer that walks amongst us?