Go to the area with the airplane. Jump on its wings to reach the lower level. Drop from the plane, then go to the left of the furthest wing (towards the front of the plane). Once you reach the rock wall, find the slightly hidden hole. Go through and follow the path along the cliff side to reach a cave with a giant typewriter. After Alan is done speaking, go on top of the typewriter. You can read a paper that reveals more of the storyline.