Two of the missing children are intercepted by Marta, who takes them to a room within her Black Daisies sanatorium. Lena manages to sneak into the facility's secret wing, where she discovers information about Nazi experiments during World War II, including those conducted by a mad scientist who wanted to create a new race of human beings using the women of Walbrzych as guinea pigs. She also discovers that Ilse was her grandmother...

Lena and the children resurface in an underground lake where they find Ada. Guided by Ilse's spirit, the small group enters the world of the Vrill. Meanwhile, Marta's henchmen, revolted by her extremism and unethical methods, kill her. Refusing to admit that Lena allowed herself and the children to sink into the surface lake, Rafal follows their trail to the underground lake and finds them. However, he can only save the children at the cost of a terrible sacrifice...