Thirty-nine-year-old cop Mylène is going through a rough patch after her split with Guillaume. What's especially painful is that she'll no longer see Justin, her ex's son to whom she's become deeply attached. On the job, she feels increasingly powerless in the face of the injustices she encounters daily. Her faith in her work is dwindling fast. Then during a routine intervention with a family in crisis, her life is turned upside down. Given the lack of proof, how could she and her partner have avoided the worst? With the power of Plan B, she'll do everything possible to alter the course of the drama unfolding between two civilians. Her journey brings her face to face with her own anger. Did she subconsciously choose this path to find out who she really is?