I was assigned to the investigation, and what I discovered in the following weeks shattered my belief that life was normal. What I found wasn't a simple matter, but a complete tragedy, an evil that had befallen an entire neighborhood, no, the entire city, no, the entire country…” Former police commissioner Hélène returns to duty to investigate the disappearance of a family: a couple and their young son, Milo. She meets with the last people they had been in contact with and interrogates them to understand how an entire family could vanish in a neighborhood where every house is made of glass. Since France entered the era of transparency, these men and women have lived in a harmonious, evil-free world, where everyone develops under the watchful eyes of their neighbors. But during her investigation, Hélène will uncover a truth as astonishing as it is terrifying.