At a remote hinterland farmhouse the body of keen photographer Idris Williams is found following an anonymous call to the police. At first it seems that the reclusive Idris was the victim of a burglary that went horribly wrong, but Mathias' instincts tell him otherwise. Idris' eerie photographs together with the discovery of a battered mouth organ - standard issue by German Wehrmacht during the Second World War - lift the lid on a generation old secret and a love story spanning seventy years. Could Idris' death be linked to a series of murky land deals made by Idris' father which disinherited his neighbour, Eric Roberts, years previously? Can Eric Roberts' only surviving daughter Enid and a letter in her possession explain the mysterious disappearance of three German prisoners of war on Welsh soil in 1944? And if so? What is the connection? Ignoring Chief Superintendent Prosser's orders, Mathias comes into conflict with a local organisation of professional men known as "The Guild", headed by lawyer Herbert Rees. But when Herbert goes missing the focus falls on his wife Nia. What was the relationship between her and Idris? Did they share more than a love of photography? When Herbert is found to have been kidnapped by an unknown assailant, Nia is forced to confess to a passionate affair with the dead photographer. Mathias discovers Herbert in a garage hideaway, shaken but unharmed and the race is on to find his assailant, the final piece of this epic historical jigsaw.