Nobody's Agent by Stuart Field

In the Small town of Finchley, upstate New York, three bodies are discovered in an old mine. Soon after, Sheriff Doug Harrison contacts the FBI for help.

Ronin Nash is an ex-FBI special agent who wanted nothing more than to finish restoring the old family lake house. Now, Nash's old boss wants him back and on the Finchley case.

Nash takes the job and travels to Finchley, expecting to solve the case quickly, but it turns out that things are not not as clear-cut as he thought. Someone in the small town has a secret, and they're willing to go to any lengths to protect it.

A riveting crime thriller, Nobody's Agent is the first book in Stuart Field's Ronin Nash series.