In the first season, Nick, who has just returned from a three-month leave following the traumatic shooting of his partner, learns he has been partnered with Ben, who has just transferred from a small town to restart his life in the big city. Ben and Nick must attempt to put their differences aside as their lives further intertwine, both professionally and personally.

In the second season, Ben is under pressure from the Sécurité du Québec (SQ) to uncover the identity of a mole at Station 19. He begins to secretly investigate his own squad, further complicating both his partnership with Nick, and their burgeoning friendship.

In the third season, the fragmented squad is reeling from the revelation that Sergeant Julien Houle was a pedophile and a mole for organized crime. As Commander Gendron scrambles to save his own career, the patrollers strengthen their bond to help them through this shocking news. Meanwhile, Nick, still rocked by guilt over his involvement in a murder, seeks closure by trying to find out what happened to his missing cousin Kaz. Ben finds love and happiness with Nick’s sister, Amelie, but struggles with the family he thought he’d left behind.

In the fourth and final season, the squad faces an eruption of events that force them together in the face of tragedy. It is a season of personal growth and professional trials with beat partners Ben Chartier and Nick Barron and the rest of the cops in 19 fighting corruption and seeking revenge.