Warnings Active: Cube Hitting Head, Orb Hitting Body, Orb Receiver

Put one portal on ground level and one portal on the level above you. Push the cube down and place it on the button, then go back up and through the door. To your left you will see an orb launcher and the telltale scorch of impact; in the center, you will see a receiver. Make one portal above the receiver and put the other on the scorchmark. Now, make one portal on ground level and put the other above the path of the moving platform. Land on it and push the cube off. Put the "ceiling" portal above the shorter of the two button platforms (there should be an illuminated one-dot icon above it; use that as the target for your portal). Push the cube through and then follow it; using your height, shoot your "ceiling" portal through the open door that you came through earlier to get back to the other cube. Go through and take the cube off of the button, then take your "ceiling" cube, place it on a wall or floor within reach and go through. Finally, move your "ceiling" portal onto the two-dot icon above the other button platform and carry the cube through. Put your "ceiling" portal above the small ledge in front of the exit door, or jump to said ledge from the two-dot platform, to continue.

Portal Walkthrough