[3] The script was inspired by the stories of Polish soldiers who during World War II underwent training in the UK in order to return to German-occupied Poland and partake in the underground struggle for independence.

The series also touches upon the challenges faced by the German military intelligence organisation Abwehr, the intelligence agency of the SS Sicherheitsdienst des Reichsführers-SS (SD), the Nazi secret police commonly known as the Gestapo and the infiltration of the Union of Armed Struggle/Armia Krajowa by the Abwehr and the SD.

Series V tells the story of the final period of World War II and shortly after its end, from April to June 1945, and is set in the newly instated People's Republic of Poland, Czechoslovakia and the American zone of the Allied-occupied West Germany.

A small division of Polish soldiers are completing their training in England and are about to be parachuted back to occupied Poland in order to carry out sabotage actions against the Germans.

The members of the division are: Czesław Konarski, major of the Polish Armed Forces; his two sons - Władek, sportsman and lieutenant of the Polish Armed Forces, and Michał, medical student; Jan Markiewicz, an architecture graduate from Praga in Warsaw, and Bronek Woyciechowski - before the war the only heir to the fortune of a Warsaw businessman.