A thick one, but a good one. I've loved the other books I've read by her and once again this one takes place in southern France. Events occur in two time periods, the 4th century and during World War II. The story has a link back to Labyrinth. In the fourth century a monk, Arinius, has been taxed with saving a document that the Christian leaders have decided is heretical. Like a few others, he disagrees and has accepted the task of taking the Codex to another land and hiding it safely away for a better time. In World War II, another man Audric Baillard is looking for the Codex, trying to keep it out of the hands of the Germans and others who would not honour it. Audric is an old man by now, but still strong and smart and working with the Resistance to save France. Citadel is both the name of a house in a small mountain village, and the name of a Resistance group, a group of women working actively to defeat the Germans. At the centre is a young woman Sandrine and as the book begins we see her becoming aware of what is happening around here and beginning to plan her group. As usual, we have strong women at the centre of the novel, in both time periods, and the men who love and honour those women. While fiction, this novel is written around real events of the Second World War, and was inspired by the massacre at Baudrigues on August 19, 1944 and the women that died there. Carcassonne was once a city of peace and tolerance and it is this legacy that Mosse honours here. A tale of love, of history, and of good prevailing in the end, this novel will grip you to the end.