Part 15

Turn around and face the door. Look up to see a pushed-out concrete slab. Shoot a portal at it.

From here, you can use either the Double Fling or the Super Jump.

Super Jump: Fire the other portal at the floor near the wall. Jump through the first portal. On the way down, shoot the portal on the slab where you are going to land. If done correctly, you will exit the portal near the wall and can hop over the obstacle.

Double Fling: Shoot a portal at your feet. While falling, shoot the same portal (the one on the ground) at your landing zone while still in the air. You will rocket out of the portal on the stone slab and fly over to the other side.

Approach the door.

Camera Shy: While facing the door, look up and to the right.

Head through the door and around the corner.

Camera Shy: After turning the corner, face the next room and look up and to the left.

A commentary node featuring Paul Graham will appear. He discusses how the puzzle was simplified to focus on the double fling due to play tester feedback.

The room contains an energy ball redirection puzzle. You cannot place portals over energy fields, and walking through one destroys your portals. Place a portal where the energy ball hits the wall, and another above the piston. This will direct the ball into a small area.

After the ball enters the first portal, immediately turn and shoot a portal where it will hit the wall in the small area with the receptacle.

Shoot the other portal at the orange light on the ceiling from the receptacle. This will cause the piston to descend.

Run onto the piston and ride it to the top. Run down the hallway.

Camera Shy: After exiting the hallway, it will be floating in the middle of the room.

A commentary node featuring Garret Rickey will appear. He explains the implementation of mid-air portal placement.

Turn around and look up to see another pushed-out concrete slab. Shoot a portal there.

Turn left and go through the door.

Camera Shy: While standing in the doorway of the small room, look up and slightly to the right.