During the rule of which Gondorian steward Isengard was lost?
EDIT: Oops, sorry, cross-post - I was re-thinking the question so many times that I had the post window open and meanwhile, you posted... well, it also seemed to me that is not much of a character trivia question... but at least you have something to answer now, Rune... TM would certainly let you take at least one guess before he himself attempts, right?

...everyone's happy.
After all, we have plenty of threads with riddles here... you might look at others meanwhile...