You are in a castle constructed with ones memories. You are there to discover what is the story behind that castle and how it came to be. After doing some discoveries you find out the terrible past of a young man. These nightmares still haunt the castle and you are the one to lift the curse.
As a kid you were afraid of water in your basement, because dad kept telling you scary stories about invisible monsters lurking in the water which would only eat human meat.
Maybe put some blood spillings in there, on the walls and such, since human meat is involved.
@ MasterOfTheMind - You really like gore don't you ? :D
Nice design you have there,but I would suggest you even that place a bit(maybe put some more objects in there and entities)