Ada and the missing children wake up in an underground tunnel, with no memory of what happened to them. While the police are interested in the Nazi treasure trail, another child goes missing, angering the locals, who believe the kidnappers are Roma. The police then raid their community, during which Luca's father is killed. Meanwhile, Lena continues her search, which leads her to a forest near Walbrzych. There she meets a strange homeless man, Sznirel, who mistakes her for a certain Ilse and gives her a mysterious key...

While exploring the underground tunnels alone, Lena stumbles upon the former Nazi laboratory. There, she discovers CCTV footage showing Ada and children who disappeared from the same laboratory. Marta, for her part, maneuvers to have the investigation taken away from Rafal. The young police officer then reveals to his boss that his father committed suicide after participating in the restructuring project of a local mine run by Marta's husband. Rafal then gives Lena a video filmed on the fateful day she was taken away from her daughter Ada. Horrified, she sees herself trying to drown Ada. Marta then discovers that Lena knows about the secret laboratory where she conducts secret experiments...