Flood — Andrew H. Vachss

Burke's newest client is a woman named Flood, who has the face of an angel, the body of a high-priced stripper, and the skills of a professional executioner. She wants Burke to find a monster for her -- so she can kill him with her bare hands.
In this cauterizing thriller, Andrew Vachss's renegade private eye teams up with a lethally gifted avenger to follow a child's murderer through the catacombs of New York, where every alley is blind and the penthouses are as dangerous as the basements. Fearfully knowing, crackling with narrative tension, and written in prose as forceful as a hollow-point slug. Flood is Burke at his deadliest … and Vachss at the peak of his form.