At the Cabin - The Northwoods Guardians, #1

In this suspenseful supernatural detective agency novel, two strangers find out they've been set up to die as part of a plot that puts the mob in league with demons to pull off the ultimate score. Can they work together to survive the supernatural threat? Laura Cassidy never set out to battle psychotic arsonists and hit-man demons. She was in enough trouble just trying to keep the dog shelter she was running afloat amid financial crisis. So when her best friend Katie McMillian and boyfreind Peter offer her a chance to get her mind off her troubles at a rustic cabin in the woods, Laura jumps at the chance for some romantic time with Peter.
Only, that's not what she finds at all. Instead, ex-FBI agent Todd Levitts shows up, and they both realize they've been set up - only they have no idea why. As the cabin goes up in flames, Laura and Todd find themselves running for their lives, suddenly in the middle of a plot involving dopplegangers, mob hit men, and terrifying demons. Together they must unravel the mystery in time to figure out why they're being targeted, and Laura must decide if Todd is someone she can trust or if he might be just one more deadly playing piece in this terrifying game.