I checked everything I thought. I did find a book that highlighted on the shelf and my character said he heard a click. But I have no idea what it did. I can't find anything.
Maybe a bug. It should move the bookshelf aside and open a hidden room.
Wait a minute. What book on what book shelf?
The quest description specifically asks you to search the "ruins around Adrasteas tower", not the tower itself! This is what I've been doing this whole time, to no avail! I even filed a bug report! You tell me I have to go inside the tower?
It's outside. From the center of the platform treat the tower as north. Go to the building to the southwest, first room has buried treasure second room has undead. Kill enemies and search that room using cautious mode.