It is 1931, the pre-war in Europe, the economy is in crisis and society struggling in chaos. A young ambitious lawyer Justus Wehner gets his first big case - the defence attorney for brutal serial killer Peter Kurten. Wehner is certain that Kurten suffers from a serious mental disorder and to prove this, he decides to sink deep into Kurten's past motivations and psyche. Suddenly Kurten's beloved wife Marie arrives who still doesn't believe her husband could be a violent murderer. Kurten and Marie slowly begin to manipulate Wehner into participating in a final crime. Wehner will have to fight for victory in a difficult case and for his own soul.