Colonia's director, Florian Gallenberger, gave an interview to br-online. Here's a summarize made by Blupp for Pottershots.net [SPOILERS]:
"the first part is an introduction into the history of the real events. then Gallenberger talks he first discovered it when he was 9 because of a teacher showing a documentary. he says you cant show everything that happened there but its possible to understand how the system of such a place works and how Schäfer was able to build something like that without showing it in detail. he thinks Schäfers main motivation was his pedophilia. the colonia was one of the biggest backeries and also made good sausages and therefore had a good reputation. Schäfer wasnt a bavarian but he liked the traditions and the image of lederhosen and good food was a basis to appear harmless on the outside.
then he talks about Daniel playing a young german student in Santiago, Chile in 1973. Emma plays his girlfriend, she visits him and its on the eve of Pinochets coup, they are drawn into it and Daniel gets kidnapped. Emma researches and finds out he is in the Colonia and despite people warning her Emma joins the sect. Gallenberger says he doesnt want to give too much away but yeah she finds him.
Gallenberger thinks the movie will be released end of this year if he gets the editing done quickly or if it doesnt work out next year. at the moment the name is Colonia but its possible that that will change."
[Full interview (in German)]