The Cerbère Squad, at the controls of Captain Pelletier, is entrusted with the file of an arson attack that has occurred in a furniture store. Now at the Anti-Gang Squad, Lily-Rose begins a new investigation at the scene of a shooting alongside her new and colorful sidekick Cindy Castonguay. Quickly, the investigators of the two departments will see the need to share important information to advance their respective investigations.

The departure of Marc-André allows Stéphanie to bring order to Quebec Security. The investigation of Anna, who still suffers from amnesia, continues. Her story touches Lily-Rose who is going through difficult times following her assault.

After the death of Marilou Magloire, The Special Missing Persons Squad takes action; although the investigation falls to sergeant-investigator Pelletier, the quartet is determined to find the murderer of Renaud's sister.