A boy's body is found in bogland along the Irish border: a case as cold as the earth that has hidden it for so long. DI Owen Sheen has sworn to get justice for the unnamed boy and digs up links to a covert British Army unit that was tasked with creating Satanic panic in the 1970s. But when a vicious murderer begins to stalk Belfast's streets, it's clear that someone refuses to let the past remain buried. Alongside DC Aoife McCusker, who must fight to restore her professional reputation, Sheen is racing to make the connections and stop a killer against the backdrop of Northern Ireland's darkest history and uncertain future.