Satyrn
First Post
so in your mind, if someone does something that can't work, and that you seeded into the story of the course of levels can't work, you should just say "Ok you win."?
in your mind I should not describe the world as it comes, but instead make it so no matter what the PCs do they win?
I would say yes. When my players do something they feel really ought to be successful, I will shuffle details around to make it successful. In this case, I might just say the item is indeed in the vault, but if inspiration strikes while they're on the way to vault, I would add an obvious clue to tell the players aren't quite right. Guards talking about the villain getting ready to take his bath, leaving that precious item unattended in his dressing room while he does so. And oh, the PCs had already passed the passageway of pipes that leads to the bath house.
Or just stick the item in the vault while he's taking his bath.