Nick Barron and his partner Jean-Pierre Harvey are shot responding to a burglary. While Barron is spared by his body armour, Harvey is shot in the head and left hospitalized for life. Replacing Harvey is Ben Chartier, a veteran constable from the Sûreté du Québec (SQ), who transferred to Montreal to escape troubles in his hometown. As officers from Station 19 deal with the challenges of police work, they struggle with their own personal challenges as well. Chartier is estranged from his family after he personally arrests his own father for drunk driving. Barron struggles with his continuing feelings for his estranged wife, colleague Detective Isabelle Latendresse. Tyler Joseph struggles with alcoholism. Jean-Marc Brouillard abuses his wife. Commander Marcel Gendron struggles to protect the station’s image in the face of pressure from the public and his superiors alike. By the end of the first season, Chartier’s former employer, the SQ, assigns him to find a mole within the station.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 Cassius 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. The third season starts in the aftermath of the mole’s suicide. The reputation of Station 19 has been destroyed by the revelation of the mole, along with other incidents such as the arrest of Brouillard for domestic violence. Cassie Clemont is discovered dead, having been brutally tortured for days. Barron and Chartier must deal with the fallout of Barron’s actions, as the station is scrutinized by an inspector from Internal Affairs.