Die schwarze Nadel.

A year after Napoleon's death, Vidocq must put an end to the all-too-frequent duels between royalists and Bonapartists. A local Bonapartist leader who has come to Paris to bring money to his leaders is provoked and killed in a rigged duel. Disguised as a businessman likely to finance the Bonapartist cause, Vidocq infiltrates the network preparing Napoleon II's return to France. The opponents are unaware that by joining this movement, they are denouncing themselves: the Baroness, who heads a secret political police force, has no choice but to have them arrested. Vidocq wants to save them. But he too is challenged to a duel...