I just started watching it, looked interesting, this guy built his own sub etc. Etc... I had NO IDEA that it was going to go the way it went. I'd never heard of this story before, so it was sort of a surprise to me, which was good.
Seemed a lot like a very self assured man and the people who congregate around him to be part of it all and help. OK, so that' exactly what it was - except turns out he's a psychopathic narcissist who just wants to kill a woman or something in his sub! Sorry if there are spoilers but the description on the page says all that also.
What got me was the people around him and how shocked they were and -- you know, how could you not know something was wrong with your "friend"?? It makes it all the more harrowing to realize that these people walk amongst us and that you could KNOW someone and not know them at all, and they are like this guy. So, it was interesting to me as I had no idea about the case nor what the doc was about, didn't even notice the tag line til later. LOL Interesting. TRULY scary. Real life horror.