About to leave on an expedition to the Arctic, Lena Opalinska learns that Ada, her long-lost teenage daughter, and the kindergarten children she was looking after have disappeared. The geologist immediately goes to her hometown, where Ada lives, and enlists the help of Rafal, her childhood friend who has become an assistant commissioner. The police suspect Ada of kidnapping the children. Marta, a philanthropist and director of a sanatorium called Black Daisies where she experiments with the medical applications of anthracite, offers her support to the distressed parents...

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...