Decazes has replaced Fouché as Minister of Police. Vidocq, no longer head of the Sûreté, is warned that a plot is being hatched against the king: ultras want to replace Louis XVIII with his brother Charles. The leader of the plot is none other than the Baroness. To achieve her ends, she intends to use a healer to whom an archangel appears at night - an archangel who bears a striking resemblance to... the baroness (!) -. Vidocq, captured and held prisoner by the Baroness, escapes and tries to prevent the planned assassination attempt on the king. But he falls into the hands of the Austrian occupiers, who threaten to shoot him...