Celine and Alexandre make progress with the investigation; they learn that on the night she disappeared, Justine left the bar with a mysterious man.

Celine is now interested in looking into the murder of young Gregoire three years prior, as the two deaths are linked by method, among other things.

Celine believes that multiple murders are connected, while Jacques refuses to admit there's a serial killer and doesn't send reinforcements.

Celine and Alex uncover the identity of a man; a new corpse is discovered; Celine figures out who the killer is.