You walk back through the cavern, wondering if the entrance will still be blocked by ice. This time, though, you are greeted by a warm breeze. Sun- light is shining on the ground near the entrance, and you walk outside.

Squinting your eyes in the bright light, you see a world totally different from the one you know. You are on a hillside. For miles and miles you can see grassy plains speckled with lakes. Nearby is a forest of towering ferns, swaying in the wind. The world before you seems strangely quiet, except for the faint rumbling of distant thunder. Suddenly, the thunder seems much closer-and louder. The thundering sound is moving through the ferns. You run up the hill looking for a place to hide. A huge shadow passes on the ground. Above you, soaring through the air, is a creature larger than any bird you have seen.

Now it is clear what has been happening. The cave is a crack in the universe, a place outside space and time. Once inside its tunnels you could find yourself at any place, at any time. If you enter again you might be sent to a place from which you could never escape. Yet that is your only hope of returning to your own place and time.