Ill Luck in Old Zazesspur

Publisher's blurb:

The ancient city of Zazesspur, in the kingdom of Tethyr, is a city in decline. To make matters worse, in the last few days swarms of vargouilles have begun haunting the city at night, preying on those they encounter and thus growing in number faster than the city can deal with. Brave and experienced adventurers are needed to combat these hideous fiends and to deal with the sinister creature that is behind their attacks... a nefarious nycaloth that is hiding via natural invisibility within the city itself!