A remote Scottish estate. A missing teenager. When a young archaeologist discovers bones at the site of her Bronze Age broch on Gallows Hill, the community of Kilbroch hold their breath. Ex-detective Callum MacGarvey came to work on the estate in order to escape from his past, but when a friend asks for his help, he cannot refuse. Missing teenager Robbie MacBride's grandmother wants answers. She doesn't believe what the family tell her, and Callum finds himself reluctantly drawn into a historic missing persons case. He suspects that everyone is hiding a secret, including George Strabane, the landowner whom Callum works for. While the police believe Robbie ran away from home more than a decade ago, not everyone is convinced. The archaeologist, Laura, ex-detective, Callum MacGarvey and Robbie's grandmother continue to investigate, while Robbie's sister, the silent Ruthie, remains haunted by her childhood flashbacks. Sometimes the truth is so dark, it's best to let sleeping dogs lie.