The Phantom’s Vice by Mindy Paige

When the FBI’s most wanted criminal leaves his DNA at a crime scene, Brett Evangeline is sure she’s finally going to bring the masked assassin to justice. The brand-new FBI agent can’t believe her luck—both in getting assigned to this case and her findings—but what she doesn’t realize is that, in the criminal underworld of Moriton, luck does not fortune the kind or the good.

When terrible secrets come to light, Brett must reevaluate everything she thinks she knows and decide which evil is worth trusting—and the serial killer with a soft spot isn’t making things any easier for her. The crazed assassin has never desired a single thing before, and now all his sights are set on Brett. And what Ghost wants, Ghost gets.
But something bigger is at play. Something sinister. Soon, it will be up to Brett to uncover the horrible secrets the concrete jungle is hiding and bring all the criminals involved to justice. Even if it’s at the cost of her heart.