Peter tries to find Olivia.
Olivia and Alt-Nina are held captive, with Alt-Nina acting as if she is our Nina.
David Robert Jones wants Olivia to turn on the lights on a pegboard like she did in a previous season.
While Alt-Nina is being electrocuted, she realizes the only person who can truly make Olivia feel enough is Peter.
September just shows up in the middle of the lab, shot.
Peter enters September's mind, and witnesses the beginning of all things.
September tells Peter they were human many generations after his lifetime, and one of countless possibilities of his future.
September tells Peter about Henry being born to Fauxlivia. An event that woudl have irrevocably altered everything that was to come.
When Peter made the sacrifice to step into the machine, Peter and Henry both ceased to exist.
He tells Peter he has managed to return in physical form. He tells him that his future was meant to spring from Olivia Dunham and he must go home.