A cold but sunny day in Berlin. Matthias Schweighöfer is back in town after working primarily in Hollywood in recent years. The 42-year-old currently plays the legendary German hit producer Frank Farian, who through his troupe Boney M became famous and then with Milli Vanilli caused a scandal: The duo invented by Farian didn’t even sing themselves. “Girl You Know It’s True” opens in cinemas on December 21st. But there are also other important things to discuss.