The mystery is very compelling at this point, and I'm already concerned about Cassie now that Legarski knows that she's onto him, but it's arguably also not sustainable. Whatever the fates of Danielle, Grace, and Jerrie ultimately are on Big Sky, I'm guessing that the resolution one way or the other will come by the end of the first season. The show is also based on C.J. Box's 2013 novel The Highway. While every TV adaptation takes liberties with the source material, the original story has a beginning, middle, and end, and it might be for the best that Big Sky goes down as a one-off limited series.