The quest to free the caged gnome Wynne for easy access to the Wasteland — failed when Low Thi kills him.
Free Wynne from his Bondage is the quest the system offers Carl the moment he finds Wynne chained in the catacomb: free the gnome and he'll provide easy access to the flying Wasteland castle, for a Silver Quest Box. It supersedes the completed "Stay out of city hall" quest — but before Carl can spring Wynne, Low Thi spears the gnome dead, failing it and forcing Carl to find another route onto the castle.
A failed rescue quest that would have been the party's ticket onto the flying castle.