An Earthquake traps most of Korg's family in their cave, but while the youngest two children were outside, they cannot free their family. Tor and Ree are not strong enough to shift the rocks. Exploring the cave, Korg finds another passage, but it is a dead end - except, in the morning when the sun rises, he can see light. He calls to Ree and Tor and they can speak to him through the tiny opening. Eventually Korg realizes a game his kids were playing earlier might hold the key to their salvation. A long log that had been lying across a boulder made a seesaw, and Korg could see how a little weight on one side might hold up or move a larger weight on the other. He tells his children how they might move the larger rocks, and they work at it just as he told them. Eventually they move the largest rocks and free their other family members.
—Jilerb