This film tells the incredible story of Bletchley Park and the Ultra Secret. Filmed at Bletchley in collaboration with the Bletchley Trust and with interviews with Bletchley Veterans the BHTV team explain the importance of Bletchley to the Allied War effort. As Sir Harold Hinsley a Bletchley Veteran and Official Historian of British Intelligence during WW2 said, Ultra shortened the war by two to four year's and that the outcome would have been uncertain without it. The film also shows how the allies used the intelligence on land, sea and air. This film shows that the success at Bletchley was not just the result of a few brilliant men and women but the result of the efforts of thousands of unsung heroes.