The Fringe bosses have shared some spoilers and teasers for tonight’s episode, ‘Back to Where You’ve Never Been,’ and look ahead to the season finale.

In a TV Line interview, Wyman and Pinkner preview tonight’s story:

Peter has been frustrated. Walter has been refusing to help him get back to his home, his timeline, and he realizes that there’s another person in these universes who’s equally as brilliant — Walternate. Of course, Peter has his own personal attitudes about what a not-nice guy Walternate is, but despite that he’s going to put his own feelings aside to ask for help. He convinces Olivia and Lincoln to take him to the other universe, and upon arriving there he finds out that many of the things he is assuming about this timeline are not, in fact, true.

They also tease that, “The meeting between Olivia and the Observer will definitely alter the course of what you’re going to see and what is to come.”

On the season finale, they call it, “One of the biggest season finales that we’ve attempted.”

Read the full, spoilery interview here at TV Line.