After the extremely long and tearful cutscene. Examine the book beside Johnny to gain a memory link,. Now proceed through the door on the north side.
Get on the elevator and take it up to the second floor. Head left, then south on the hallway and you'll find Johnny in the control center. Interact with him then take the elevator to the third floor.
Once again follow the path to the left side and interact with Johnny who's standing in front of the cetrifuge, then get back to the elevator and up to the fourth floor.
Turn right as you exit the elevator and enter the through the door on the north. Talk to the man in front of Johnny, then approach the window and head back to the first floor.
As you exit the elevator, turn left and enter through the door on the north end.
Once you enter that room you're literally watching the ending, but you're still not done here.
When you get to the very last part of the game, just keep heading towards the left and speak to every person in the area that's not greyed out. Speak to Eva last and the game will officially end. Great story!