You turn and walk back out of the cave. It should be dawn by now, but, as you grope your way toward the entrance, you can’t see any light coming into the cave. You press against the walls, feeling for an opening. Your hands pass across something cold, wet, and hard. Ice! 

The entance is sealed by it. Blocks of ice protrude into the cave. You step back, feeling confused and helpless. You wish it were just a dream. You retrace your steps a way, trying to think clearly. You know that your only chance to get out of the cave is to follow one of the two branches before you.