Chasing Ghosts — E.A. Copen

How far is too far? Every cop has a case that keeps them up at night. For BSI agent Judah Black, it's the disappearance of a little girl named Mia. But when the shady vampire, Marcus Kelley, bullies Judah into an off-the-books job tracing the source of a mysterious supernatural illness, Judah learns that Mia has been under her nose the whole time. And the child's life hangs in the balance by a thread. To save her, Judah must put her own life on the line as collateral. Even if she succeeds in curing Mia, Judah may have to hand her over to an even worse monster. With the bodies piling up and the clock ticking, Judah may find she's on the wrong side after all.