Petra Epperlien grew up in Chemnitz, a town that for a few decades was re-baptized into the new faith of the German Democratic Republic: Karl Marx Stadt. A socialist Oz of sorts, the city was supposed to be an example of efficiency and egalitarian prosperity. But for Epperlein, who co-directed the film, this was, simply and nostalgically, the town of her childhood. Then the heavenly surface of life in Karl Marx Stadt was pierced by her father’s suicide, a mystery the film seeks to unlock 25 years after the fall of the Berlin wall. Through interviews and investigations into the archives of East Germany’s secret police, the film brings back to life the ghost of collaborationism, the specter of guilt and the traumas of the past, in a tough, unforgiving black and white that is nonetheless stylistically exquisite.