Convinced that her missing dad is in danger, Ida follows his trail to a town in the French Alps. A second disappearance brings an old case to light.

As Ida and Jaro look to old VHS tapes for clues, a suspicious Giovanna visits the Arcacia lab. Trouble brews ahead of the annual festival of Lévionna.

Gio and Ida find common ground as they explore hidden mountain terrain. Jaro and Roméo seek out a recluse who may know the truth about Roxane Vial.

Gio's theories create cracks in her marriage. Ida tries to make sense of DNA tests as Jaro and Roméo visit a psychiatric hospital in a state of chaos.

Jaro and Gio pair up after her son makes a disturbing discovery in the mines. Roméo is the guest of honor at a tense dinner with Hari and his mother.

As terror ensues inside the mine, a riot breaks out at the Arcacia lab. Gio desperately attempts to locate the group in the tunnel before it's too late.