I would imagine that the developers put clues about the Witch's house in a book in the game. I'm not sure if I'm alone, but the reason I like this game is because it does not hold your hand and makes you think things through.
There are games with no hand-holding and then there's Original Sin which shames games with no handholding by actually withholding crucial information from you, being deliberately vague, hiding game progress behind pixel hunting and bad camera, and double player/character perception checks where certain things need to be spotted by the player but other are happily discovered when your characters' perception is high enough.
I'm all for games getting out of this casual hole that devs have dug in themselves into for the sake of greater sales, but Original Sin is not doing it 100% right.
