Damien uncovers a secret that sends him racing back to his childhood home. Unable to shake her suspicions, Lucie digs into her husband's past.

The Mantis makes her next move, Achille finds a crucial clue linking the victims, and Damien pays a visit to his mother's psychiatrist.

When Jeanne receives a live video stream of the next victim, the team scrambles to stop a murder. New clues to the killer's identity emerge.