By intervening in Marseilles to capture "Baba" Aroudj, Caplan and Walter interfere in an investigation into a bloody heist, committed ten years earlier in Aubagne. Commander Guido Frankeur, who never dropped the case, intends to charge Caplan and Walter for their interference. Unless the two Parisian cops help him to ruin the Turkish Mafia case in league with the Marseilles mobsters.
