Margaret, 35, has a history of violent behaviour which has cost her a romantic relationship. She has moved back in with her mother Christina, a fragile, immature 55-year-old woman who blames Margaret, her firstborn, for ruining her dreams of a career as a concert pianist. In a state of unbridled fury during an argument, Margaret hits Christina. The law steps in, further complicating family dynamics. As she awaits trial, Margaret is forbidden from coming into contact with her mother or within 100 metres of their home. This only intensifies her desire to be closer to her family. Every day, Margaret appears at this 100-metre threshold to see her 12-year-old sister Marion and give her music lessons.

On February 27, 2009, pupil Benjamin Feller commits a crime which he has meticulously described beforehand in a diary entry. He goes to the post office to send the diary entry to his teacher before he shoots his parents and turns himself in to the police. His teacher Esther Fontanel tries to understand the events in retrospect. But as the journal’s addressee, she is increasingly targeted by the police herself.

Freed after 20 years in prison, the child killer Guy Beranger found refuge with the monks in Vielsart, a small village in Belgian's Ardennes. He is placed under the protection of a young Federal Police's inspector, Chloé Muller. A little while after his release, a little girl disappears.