Vidocq and Desfossés have joined the privateers, but Vidocq wants to return to land. Armed with the papers of a dead soldier, he disembarked at Boulogne and joined the army. Too late, he learns that the dead soldier belonged to the Olympiens, a royalist secret society. After refusing to kill a traitor for them, Vidocq realizes that he is in danger. Knowing that the police will intercept the mail, he writes to Annette. Will Flambart arrive in time to save Vidocq and foil the plot ?