 1945. The last two months of World War II. American and Russian intelligence services are desperately looking for a secret machine which enables Germans to decipher Soviet code. Functioning of that machine is connected with the biggest mystery of WWII - construction of the atom bomb in the underground laboratories of Lower Silesia complex "Riese". The tracks lead to the Tschocha Castle on Lower Silesia, Poland. Polish agent Johan Jorg is employed in the castle as a cryptologist. He passes secret informations to the radiotelegraph operator, Natalia, who transmits them to the army group lead by the cryptologist and commodore Howard Campaign and major Andrzej Czerny from Polish intelligence service. Russians are in better situation because their agents are 20 km from Tschocha. The castle is reigned by Hans Jacob Globcke - the head of security who is supported by the ruthless Matheas Beer. Globcke discovers that Jorg released Polish prisoner of war - Andrzej Czerny. He also suspects Jorg to be allied spy and frantically starts to search for proofs. When Natalia is captured by Globcke it seems there is nothing which can save Jorg. A group of commandos is sent the castle to renew contact with Jorg. Despite their sacrifice and heroism Globcke carries the cipher machine off the castle. However, their efforts are not wasted. Compaigne, Czerny, Jorg, find the machine but they do not receive any commendation from their superiors. They are dismissed from the army.