From January to September 2022, at the headquarters of the Narodowy Bank Polski, there was a temporary exhibition dedicated to the series of secret banknotes codenamed E-71. These banknotes were designed and produced during the communist regime in the event of an armed conflict between the Soviet Union and its satellites and NATO countries. The history of these banknotes, as well as many separate mysterious threads unexplained to date, could serve as the basis for the script of an action movie. In one of the vaults of the Narodowy Bank Polski there were three wooden military containers marked "secret of special importance", which had been stored for decades. After the official opening, it turned out that three sets of materials for producing banknotes under the codename E-71 were found in these special containers. The exhibition consisting of 12 showcases presented the entire series of E-71 war banknotes, including unique sheets of cash symbols with denominations from PLN 1 to PLN 2,000 (11 denominations in total), trial banknotes and graphic designs from the "Polish Cities" series, developed by Andrzej Heidrich in the 1960s, as well as technical documentation describing the launch of the production of a secret series of banknotes in the event of war outbreak. E-71 series of banknotes were also presented in NBP regional branches, and today some of them can be observed at the exhibition in the NBP Money Centre in the Central Bank Room.