Céline is back in Quebec City and investigates the murder of a civil engineer – found encased in concrete in a Château Frontenac bathroom. Alex, on compulsory leave for post-traumatic stress disorder, unofficially investigates the case, going undercover at the château. Sophie joins her father William to hunt industrial secrets related to the city's major engineering projects. Céline is partnered with rookie detective Daphne.

• Isabel Richer
• Alexandre Landry
• Didier Lucien
• Gilbert Sicotte
• David Boutin
• Daniel Parent
• Dorothée Berryman
• Sébastien Ricard