I read this story for my English class last year.
The man starts out in a castle which he has lived in his whole life. He can't go through the forest because he always leads back to the castle. He then tries to reach the top of the castle and somehow ends up on solid ground. He wanders around for a while before he crashes a party, and everybody's terrified of him.
The man eventually finds a mirror and realizes he's a monster.
I'm pretty sure the story ends with him fleeing back to his castle.