If it's still in production it might be that even they don't know it all yet. I have a lot of experience with that kind of work (conducted over 200 interviews for documentaries last year alone). More often than not you make a story in research phase only to find out that's really not the case once you start interviewing. Then you find yourself a real story, but you have to start from somewhere. Synopsis in documentaries is more of a Wishopsys, real script comes through interviews. One reason to conduct real, thorough, questions during interviews and not during research is so that you get genuine response. Making a documentary is a like a game of table tennis. You go back and forth numerous times during production and post.