Winter's Last Victim. Holly Winter Cozy Mystery Series, #4

Rob Frost is so close to finally digging up the truth. He'll do anything to be the first to find evidence of the secret civilisation he's been searching for since he was a child. But when digging under the cover of darkness draws more attention than he'd planned, he discovers that something deadly is lurking in the woods. Will Rob be able to keep his head in a sharp situation? As Holly's not-boyfriend George is moving away from Little Wemley for good, she's more than happy to distract herself with a new case, so when Rob needs her help, she jumps at the chance to work with him.
It may also have something to do with her and Rob having their own unfinished business to attend to. She soon discovers her business partner might have finally dug too deep when both the government and a gang of crime lords get involved. But what could they possibly want with an ancient artefact? It's not long before Holly and Rob realise what's really at stake. What will they do when the fate of humankind is in their hands?