Showing Living with the Dead by Kelley Armstrong

Robyn Peltier has always lived a normal life. So when her boss is murdered and she is named prime suspect, she is way out of her depth. As the bodies pile up only her friend Hope, and Hope's somewhat spooky boyfriend Karl, are on her side.

Hope, meanwhile, has a few secrets of her own. Namely that she is half-demon, and her 'spooky' boyfriend is actually a werewolf. Hope also knows that Robyn has accidentally stumbled into a bloody supernatural turf war. And the only way she can keep her friend alive is by letting her enter a world she's safer knowing nothing about . . .