Bullets — Steve Brewer

When a contract killer bumps off a high roller in a Las Vegas casino, a tangle of romance, gambling, and gunplay follows. The killer, Lily Marsden, is a mysterious and cold woman who is a true professional. But soon, the casino owner, his henchmen, and the victim's two -brothers are on Lily's trail.
Former Chicago cop Joe Riley is pursuing Lily, too. She cost him his job as a homicide investigator when suspicion of a bookie's murder fell on him. Joe is certain Lily killed the bookie, and he's tracked her across the country to Vegas.