Tour the deep dark world of the East German state security agency known as Stasi. Uniquely powerful at spying on its citizens, until the fall of the Berlin Wall in 1989 the Stasi masterminded a system of surveillance and psychological pressure that kept the country under control for decades. Hubertus Knabe studies the Stasi — and was spied on by them. He shares stunning details from the fall of a surveillance state, and shows how easy it was for neighbor to turn on neighbor.

Hubertus Knabe: The dark secrets of a surveillance state

The dark secrets of a surveillance state

In the shadows of the Berlin Wall's fall, the Stasi's intricate surveillance web illustrates the dark art of controlling societies.

Through a vast network of informants, the Stasi epitomized the chilling ease with which neighbors can turn against one another.

Despite its formidable intelligence arsenal, the Stasi's downfall underlines the inherent fragility of oppressive regimes.