When a man is shot dead on Bonfire Night, DI Wesley Peterson realises this will not be the quiet month he was expecting. Patrick North's body is discovered in woodland connected to the 18th-century estate of Nesbaraton Hall. North had been an employee of the Smithsons, the estate owners who are away on holiday. But when an anonymous letter threatening to abduct the Smithson son is uncovered, Wesley fears North's death might have been collateral damage in a sinister kidnapping plot. Meanwhile, archaeologist Dr Neil Watson unearths a hidden grotto in land that was once part of Nesbaraton. The discovery of a skeleton and evidence of rituals raise questions about strange occurrences, past and present. Then a resident of the nearby village is killed in a near-identical shooting. A race is on to find the killer, before they strike again.