Stasi: East Germany - The Darkest Recesses of the Totalitarian Mind (1997)

About one in 50 adults in East Germany collaborated with East Germany's Secret Police. Relative to population, it was the largest secret service in the history of mankind. 

"Shield and Sword of the Party" is what the Stasi calls itself. the Party dictatorship never dares not to face its opponents. 

Instead, the Stasi has to keep all dissenting opinions under control. The goal is a total surveillance society, everyone informing on everyone.

"STASI" takes a look at the extent of Stasi work: including the Ministry's enormous headquarters in Berlin, local offices, detention facilities, disguised isolation camps, hidden bunkers, reconnaissance planes, eavesdropping stations and East Germany's secret execution site.