Dorothy Martin and her husband, retired Chief Constable Alan Nesbitt, are invited to join their close friends Nigel and Inga Evans at a Welsh music festival where both Nigel and Inga will be performing with the world-renowned conductor Sir John Warner. Amid the glorious surroundings of Welsh castles and the history of long-ago battles, the stage is set for a most enjoyable festival. However, when a tragic accident takes the life of one of the choir, and the same fate befalls another performer, Dorothy and Alan find themselves in the midst of an investigation as tumultuous, passionate and complicated as any opera.