While Martin turns his attention to Alice's family, Irène goes rogue to investigate another friend of Perrot's. A prison brawl puts Diane in danger.

Hirtmann strikes a deal for one last visit with Diane, disturbing videotapes reveal a fourth figure in the ring, and a secret alliance comes to light.

With time running out, all sides race to uncover the identity of the fifth man. As Hirtmann's endgame becomes clear, Martin faces an agonizing choice.