After receiving bad news about her father, Morgane takes a train trip where she notices suspicious signs of a possible kidnapping, while trying to avoid Karadec who may reenter her life.

Troubles mount at DIPJ Lille. Morgane fails her exam, Karadec's linked to her mother-in-law's death, and Céline's son faces murder charges. Removed from the case, she arranges a Murder Party to prove his innocence.