This is the second part of the twentieth level of the game, and takes place within Test Chamber 19. The player must utilise Flinging and precise portal placement in order to proceed.
Wait for the Unstationary Scaffold to move closer to the Incinerator. Fire a portal on the wall ahead but make sure the portal is above the handrails.
Place a portal on the wall nearest to you and jump through that portal.
Turn around and shoot a portal as high as you can on the same wall. Put the other portal on the center of the floor and fall through.
Run to the left until you reach a place with a set of stairs and a catwalk.
Fire a portal on the wall above the catwalk. Place the other portal on the floor and go through.
Go through the door on the wall to get in the room. Go up the stairs and go to the end of the catwalk.
Fire a portal behind the fence and the put the other portal on the wall next to you and go through.
Go through the door and walk forwards. Shoot a portal on the wall behind the huge fan on the left and place the other portal on the floor and go through.
Turn to face the area above the Goo and fire the other portal on the wall ahead. Go through the portal.
Walk to the door on the wall on the left. Fire a portal on the wall next to you and the other portal on the wall above the catwalk. Run through the portal to get on the catwalk.
Head for the other end of the catwalk and go down the stairs. Fire a portal on the floor and place the other portal on the wall above the platform higher up. Go through the portal.
Shoot a portal in the corner facing the broken catwalk. Put the other portal on the floor below yourself and jump through.
Go up the stairs and jump over the handrail into the broken transportation tube.
Wait for the end of the ride. Then jump down to the test chamber and walk past the Material Emancipation Grill.
Go stand on the button and fire a portal on the wall through the opened door. Place the other portal near you and go through.
Head for the elevator shaft and jump down.
Shoot a portal on the floor and put the other portal on the white surface behind the fence. Go through the portal and duck.
Walk towards the two moving pistons and go stand on the one that goes higher up. Wait for the piston to be extended and then fire a portal on the surface above your last portal.
Go back to the portal you've placed before and jump through it.
Wait for the larger piston to start extending and then jump on it. Go to the area at the end of the piston.
Turn left and fire a portal through the small hole. Wait for the piston to extend again and then go back to your portal.
Go through the portal and place a portal on the wall opposite of the portal next to you. Jump through the portal.
