Exit strategy - Kelley Armstrong

From the author of the acclaimed Women of the Otherworld series comes an exciting new heroine whose most secret identity is both lucrative.and lethal.

Regulars at Nadia's nature lodge don't ask what she does in the off-season. And that's a good thing. If she told them, she'd have to kill them. She's a hit woman for a Mafia family.
Tough and self-sufficient, Nadia doesn't owe anyone any explanations.
But that doesn't mean she always works alone.
One of her contacts has recruited her in the hunt for a ruthlessly efficient serial killer cutting a swath of terror across the country. The assassin is far too skilled to be an amateur-and the precision of the killings is bringing the Feds much too close to the hit man community for comfort.

To put an end to the murders, Nadia will have to turn herself from predator to prey as she employs every trick she knows to find the killer. Before the killer finds her.