Take the door that leads west out of the room. There's nothing currently of note in the next room so go through the next set of doors. You'll come to a room and Batman mentions that he needs to find another way around so head to the left. If you follow the conveyor belt, you should see a door with a giant red button next to it. Hit the button to open the door and crouch under it. Hop off the belt and the grapple up to the ledge. Head into the bigger room and the grapple up to the vantage point for another stalker section.
This is pretty short but you won't be told what to do. Just go from vantage to vantage until you're behind the enemies (there are only three). Drop down behind the lone enemy and do a silent takedown. Then go down the stairs and do a double takedown on the enemies there. Go back up the stairs and jump through the window for good measure. Just cross to the door in the next room (or play with the giant Harley statue for fun).
