The Corrector (an Evin Hart novel)

Evin Hart's orderly life in a small seaside town is torn apart when she sees something she wasn't supposed to: gang-affiliate Mose Hickson's nasty little secret. A body washes up on the coast several days later, dragging Evin further into a dangerous maelstrom. Turns out, she was one of the last people to see the victim alive. Rapidly forced into unfamiliar territory, Evin Hart is out of choices. She risks everything she ever had and descends to places she's never imagined.