Nights and Days is a family saga of Barbara Ostrzenska-Niechcic, (played by Jadwiga Baranska) and Bogumil Niechcic, (played by Jerzy Binczycki) against the backdrop of the January Uprising of 1863 and World War I. The film is a rather straightforward and faithful adaptation of a novel by Maria Dabrowska with the same title. The plot is woven around the changing fortunes of a noble (upper-class) Niechcic family in the pre-WWI Poland. There are two main crossing threads: a social history one and an existential one. The cinematographic version is a condensation of the 12 part award winning TV serial of the same title and using the same cast and producers.
During World War I, a German U-boat sinks a British ship and takes the survivors on board. After it takes a wrong turn, the submarine takes them to the unknown land of Caprona, where they find dinosaurs and neanderthals.
A newly arrived governor finds his province under the control of the corrupt Colonel Huerta. To avoid assassination by Huerta, he pretends to be weak and indecisive so Huerta will believe he poses no threat.