St-Cyr and Kohler are shipped hastily from Paris to Avignon to investigate the violent death of a young woman in the Palais des Papes. The victim is the scion of a long fallen aristocratic family and a scholar of medieval history. She is also a singer who is desperate to join the Madrigal group for whom she already designs and makes costumes. Big on local colour, noir atmospherics and historical detail, the plot is a complex mix of politics, sex, drugs and professional jealousy. But after much self doubt, fear and another death, St-Cyr is finally able to discover the truth - but only with the help of a complex coded journal left behind by the victim.