Spies Beneath Berlin

Spies Beneath Berlin tells the extraordinary true story of the top secret mission to build a spy tunnel under Berlin, one of the most heavily guarded cities in history. In 1954, at the height of the Cold War, Britain and the United States launched an ambitious covert operation. Against a background threat of nuclear Armageddon and World War III, they targeted Berlin, a city cleaved in two by East-West tensions. Their mission: to gain advance notice of a possible Soviet attack by tapping into Red Army communications.

Spies Beneath Berlin, Thursday at 10 p.m. on PBS 6.