Another corpse, that of an adult, throws the investigation into disarray. Who could this woman be, found in a grave that isn't hers? Upset by his mother Catherine Valant's revelations, Romain struggles to keep his cool and could well be sidelined from the investigation by Noémie... who, for her part, decides to finally face her own demons by agreeing to a dive with Hugo. A surprise visit from the prosecutor could then definitively put an end to Captain Chastain's mission... if it weren't for the unexpected and surprising appearance of someone we never thought we'd see return to Avalone...