This new season begins with Nick and Ben working to avenge the death of Nick's sister and Ben's lover, Amelie. In the process, they find themselves pulled into an escalating cycle of mob violence and revenge.

While Nick is determined to move forward, Ben fights to keep his faith in justice and in himself. As a raging gang war intensifies, the entire squad is pushed to their limits and forced to depend on each other more than ever.

Season 3 sees the return of beat partners Ben Chartier and Nick Barron, as they navigate the blurred-lines between Montréal politics and organized crime, while the squad searches for redemption and begins to heal from Season 2's traumatic events including a horrific school shooting, and the shocking revelation that their beloved sergeant was a pedophile.

The second season begins with Barron and Chartier responding to reports of a snake at a daycare centre. Chartier encounters an armed civilian: Barron's cousin Cassie Clemont. Barron's unsavoury relationship with Clemont makes Barron the prime suspect of the SQ's investigation into the mole in 19. When Chartier brings Barron into the investigation, Barron and Clemont burgle a suspect's house and make a rash decision that endangers both of them.