Welcome to the world of Susan Pulaski, an unconventional and unusually subversive Las Vegas police behaviorist who’s already been canned once and has never been needed more. In Sin City, someone is ritually murdering handpicked victims, each with dirty secrets in their pasts. The killer’s gimmick: Not only does he leave behind parts of the victims’ bodies, he also writes obscure mathematical formulas–in their blood.

Pulaski doesn’t have a clue what the codes mean. But she knows someone who will. Darcy O’Bannon is a twenty-six-year-old whose autistic savant skills are perfect for unraveling the thinking of Vegas’s most savage serial killer, peering into a numerological mystery that stretches back hundreds of years.

With her own life one spark away from going off the rails, her department turned against her, and the lives of those she cares most about in jeopardy, Pulaski hunts for dangerous prey in the shadow of the Strip–with herself as the perfect bait. The incomparable William Bernhardt brings to life America’s most fascinating city and invites us to join one woman’s fight to stay sane, stay alive, and keep a killer from making the most shocking score of all.