The detective Victor Deferre inquires into the disappearance of a girl called Victoire Marchand. He gathers various testimonies, clues, and fingerprints collected by the police force. Thanks to his investigation, he finds a plausible a suspect, Carla Loumis, who was the assistant of professor Pauwells. However, Pauwells was withdrawn in order to continue its research in an isolated laboratory. Written by Arnaud M. St Martin de Veyran