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...