In the end it went nowhere. The whole 4 episodes are, essentially, about how the creators of the show pick up an idea, juggle it for a couple of minutes and then replace it with another idea, as if it's a brand new and shiny toy.
There were psychological thriller elements, there were potential aliens, there were multiple multi-layered conspiracies, there were potential outsiders, that may know stuff that would click with the knowledge main characters have... They even had something that looked like a cult. Oh, and yeah, the main premise had a "mysteriously missing airplane".
None of that led to anything, and was ruined by the ending. I won't spoil it, but it just did not fit. If I strip away all the nonsense mentioned above, and leave only main premise and the ending - there is potential for a good story in-between. Even with several good "messages". But all this jumping from idea to idea without even providing proper closure to any of them simply destroyed all suspense of disbelief.
There was so much potential. Actors were quite good (except places, where the girl was not able to chose whether she can lip-read or not in the last episode), it was atmospheric, and well shot. But that's not enough for a sci-fi show. The story is king, and here it's a very poor king.
