City of the lost / Kelley Armstrong.

Welcome to Rockton: a secret town cut off from the rest of the world. If you need a place to hide, this is the perfect place to start again. There's just one catch. You can't leave. Even if there's a killer on the loose. Detective Casey Duncan has a dark past, and it's about to catch up with her. When her best friend Diana is attacked by an abusive ex, the two women realise they have to disappear, fast. Diana's heard of a hidden town that's so remote it's almost impossible to reach. A town that desperately needs a new detective. Casey has barely arrived in Rockton when a body is discovered. A man's been murdered and there's no time to waste. Casey's job won't be easy: everyone in town has a secret. Meanwhile her boss, Sheriff Eric Dalton, is a brooding, troubled man who's hard to read and even harder to please. With no chance of help from the outside world, Casey must rely on her wits and experience to solve the case. But she's running out of time. Rockton's killer is on the hunt, and this deep in the wilderness, no one is safe.