Warning: Spoilers for Westworld Season 2's first two episodes.
The big mystery of Westworld Season 2 is "The Door". What is Ford's new game, how does it link to the rampaging, self-aware hosts, and what does it have to do with the Man in Black? We're going to be cracking the case weekly.
Westworld Season 1's big mystery was "The Maze", a hidden story within the trappings of the futuristic western theme park. William/The Man in Black believed it to be a secret level in the park, but as people kept telling him, it wasn't for him at all. Instead, it was for the hosts; the maze wasn't anything physical, rather a theory in how the robots could gain consciousness by giving them their own internal voice, left behind by deceased park creator Arnold. At the very end of Season 1, Dolores "solves" the maze, becoming her own being and killing Arnold's partner, Ford.
After The Maze, apparently, comes The Door. Showrunners teased that Westworld Season 2's big mystery heavily before the premiere, and now the show's here, we're on the trail. The second episode, "Reunion", revealed a lot of new information, but first let's go back to the premiere.
The Door Is A Game Made By Ford For William
The Westworld Season 2 premiere wasn't heavily focused on The Door, with most of the mysteries raised instead around Bernard and his shocking murder of all the hosts. However, one key scene was very illuminating. William (the Ed Harris vintage) stops off at a camp in the now-upended Westworld where he's approached by the host replica of young Ford who explains this part of the new narrative. The exchange - still our clearest tease of The Door - is below in full, with the key parts marked:
Ford: Are you lost?
William: No, I don't believe I am. In fact, I feel like I just arrived.
Ford: Watch out William.
William: The stakes are real in this place now. Real consequences.
Ford: Question for you is, what next? Have you achieved all you wanted?
William: Folly of my kind, there's always a yearning for more.
Ford: That's what I always appreciated about you. You never rested on your laurels. You made it to the center of Arnold's maze. But now, you're in my game. In this game, you have to make it back out. In this game, you must find the door. Congratulations William, the game is meant for you. The game begins at the end, and ends where it began.
William: Even now, you still talk in code?
Ford: Everything is code here, William. You know that more than anyone. Don't worry, the game will find you.
William: Well then, guess I don't need you anymore, Robert.
This dialogue exchange makes several things clear. Chiefly, while the Maze was Arnold's and not for William, The Door is made by Ford explicitly for the Man in Black, presumably as part of the "new narrative" that started with Dolores' rise to consciousness. This changes how we view the events of Westworld so far; while Ford tried to dissuade William in Season 1, he was still very much part of his longer, multi-season plan.
In Episode 2, we learn that not only is the game for William, it's just for him; when he tries to get El Lazo (now played by Giancarlo Esposito) and his men to join him, they all commit suicide, with the chief reminding in Ford's language that the Man in Black must go alone (although he does seem to have Lawrence for company).
Based on everything that's been said so far, The Door seems to be something of a challenge to William's new found freedom, with him tasked to find some sort of escape from the park, possibly due to the new order. Of course, given that the Maze was really a metaphor, there's sure to be some greater purpose. Indeed, the ending/beginning "code" definitely indicates some greater plan is afoot.