Après recounts the aftermath of a tragic event that suddenly arose in Lac Sabin, a small town in the Laurentians. The story begins in the seconds following the disastrous event and depicts the physical, psychological and social consequences of this tragedy that no one could have foreseen or avoided. Nothing will now be the same in the quiet municipality. It is fear, mourning, incomprehension. There are the victims, the survivors and all those around them who try to understand the irreparable.