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When you solve the mystery and roust the tanner, you find a letter to go to the Umar Hills and buy a certain book. I didn't go there immediately.

Instead I happened upon the Tiris at Tradmeet Spoiler
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I killed Rejiek and the skindancer at Trademeet and restored Tiris. Is there anything to do in the Umar Hills now? I went and the Book Merchant is out of books.

Which bookseller is out of books? The one in Umar Hills? There should be a guy there which sells only books no matter whether you have killed the skindancer.
Well, I've never did this quest because I am a do-gooder [img]smile.gif[/img] Nevertheless, I am always doing the Tiris quest in Trademeet - and I am always finding the bookseller present in Umar Hills.
Therefore, yes, I think there is something to do in Umar Hills.
Note: The final result of that doings is usable only by evil characters. If you aren't evil or if you haven't evil characters in your party then don't waste your effort.