Police strive to pinpoint the connection between the elusive leader of Niko's prostitution ring and the Butcher of La Villette, who is still on the run. There is more tension between Laure and Gilou, as Gilou prepares to leave the team. Judge Roban finally gets proof of Arnaud's betrayal and his reaction is unforgiving. The screws tighten on the Courcelles bribery investigation. Szabo finds Josephine's Achilles' heel and uses it to blackmail her back into his clutches.