 The first two episodes tell the story of the amateur radio hams who listened to German Morse code broadcasts during World War II and passed their transcriptions to mathematicians and computer programmers at Bletchley Park who decoded the German "Enigma" codes, amid great secrecy. By uncovering the Germans  military plans, it is estimated that they shortened the war by between 6 and 12 months, and saved thousands of lives. The third and fourth episodes recount the propaganda programmes that were broadcast from Woburn Park, with the aim of demoralising the German military and general public.