The Cleansing (The Abbey Rhodes Mysteries) by Mitchell S Karnes

Detective Abbey Rhodes is drawn into a series of complex murders after receiving threatening messages from Skylar, a teenage psychopath she previously helped incarcerate. Each victim is discovered face down, with letters carved into their hands and foreheads, indicating a meticulously staged crime.

As Abbey delves deeper into the investigation, she uncovers a pattern and realizes the murders are a part of a larger plan orchestrated by Skylar and an unknown accomplice. Abbey must also confront her own traumatic past and complicated relationships, including her growing feelings for Dallas.