"People will die," says the panic-stricken woman outside police headquarters. She has been standing in blazing sunshine for more than an hour, and refuses to speak to anyone besides Commissaire Adamsberg. Her daughter has seen a vision: ghostly horsemen who target the most nefarious characters in Normandy. Since the Middle Ages there have been stories of murderers, rapists, those with serious crimes on their conscience, meeting a grizzly end following a visitation by the riders.