Like every day, Alicia takes her son to school. Michael, a teenager overwhelmed by his mother's protection, knows that he can't do much. She is determined to prevent him from being recruited by gangs that spread terror in neighborhoods with invisible borders where every step taken has to be calculated. This is the story of Alicia, the day her son doesn't return from school, and of Michael, the day his miscalculated steps lead them both to the abyss.