I knew about Estonian filmmaking through November and Kratt, but I wasn’t familiar with writer/director/actor Mart Sander (Eerie Fairy Tales, Behind the Random Denominator) or how much he's been working until this film, The Sixth Secret, landed in front of me. Watching it makes me wonder why his movies haven’t received more attention. The movie begins sometime in the 1920s with a couple of London police officers r…