Petra Epperlein at the Stasi Records Agency in Karl Marx City (pepperandbonestwo)

What, not everything dramatized in the Oscar-winning The Lives of Others was true to life?

That’s only one of a long list of eye-openers in the absorbing and fascinating Karl Marx City, a historical tour of the not-so-distant past that doubles as a personal exploration. The wife-and-husband filmmaking team of Petra Epperlein and Michael Tucker (Gunner Palace, The Prisoner or: How I Planned to Kill Tony Blair) take two interwoven paths. They look back at Epperlein’s hard-working, conventional family, which prospered in the former German Democratic Republic, aka GDR (1949–1990); and immerse viewers in the apparatus and mechanism of what George Orwell would have called the Thought Police. (The documentary recently screened at the New York Film Festival.)

The objective of co-director Epperlein’s on-camera investigation, carried out with considerable trepidation, is to find out whether her father was an informant for the octopus-like Ministry for State Security, aka the Stasi. A decade after East Germany was absorbed into a unified Germany, her father, Wolfgang, burned all his letters and photographs before hanging himself in the garden of the family’s suburban home. It is estimated that during the Stasi’s heyday, nearly 200,000 East Germans out of a population of some 17 million reported on their friends, family, and neighbors.

Looking like Robin Wright in black leather, and armed with her boom mic, Epperlein accompanies Tucker’s camera to interview her mother, who reveals that in 1990, Wolfgang received an anonymous letter accusing him of working with the Stasi. All roads here lead to the Stasi Records Agency. There, archivists piece together 16,000 bags of documents shredded once the Berlin Wall came tumbling down and Stasi employees began covering their tracks. Within the archive are 41 million index cards and 111 kilometers of files.

According to historian Hubertus Knabe, the premise of Florian Henckel von Donnersmarck’s 2006 film, The Lives of Others, was filled with mistakes. In that slow-burning thriller, a Stasi agent has the wherewithal to interfere in the investigation of two artists. Knabe, however, counters that no one had the power or independence to go rogue and help a victim.

Instead, the expansive network was highly bureaucratic and hierarchical, as well as fueled by paranoia. Its purpose was to serve as a so-called “prophylactic” for the communist state, to decipher what its citizens were thinking before they acted out. Given that dystopian novels and films have been all the rage recently, the film is a splash of cold water; it’s the real deal, with accounts straight out of John le Carré’s Cold War–set novels.

Knabe and other archivists and historians reveal how the bratwurst was made, so to speak. The film’s most fascinating revelations are the grainy black-and-white videos of citizens under interrogation or surveillance in a park or on a city street. Mixed into the soundtrack are samplings from Communist anthems, Stasi propaganda films, and original recordings of bugged conversations and telephone intercepts. This is material ready-made for a documentary; viewers might wonder what took filmmakers so long.

Equally involving are the circumstances or possible motives behind Epperlein’s father’s suicide. For answers, Epperlein returns to her rust belt hometown, Chemnitz, formerly known as Karl Marx City in the GDR. Reportedly once home to 12,000 informants, the city of about 240,000 is now notable for having the lowest birth rate in the world as of 2006, according to the narration by Matilda Tucker, the filmmakers’ daughter. It was also the site of a secret prison that held 30,000 political prisoners. The stark, grim, black-and-white cinematography adds a ghost town ambiance and serves as a nod to the surveillance footage.

Unlike many nonfiction filmmakers who frame a subject matter through a first-person point of view and yet remain a distant figure, Epperlein has a remarkable and resonant family history to pass on, in which the past feels immediate.