From the back cover:
This 1E/OSRIC supplement contains a revised version of Midnight Oliviah and Last Call Oliviah adventures, which introduce "The Lands of Lunacy" setting with a bonus map section all in one place!
Oliviah has fallen mysteriously ill and is only concerned with "Her Lovely" Doris Mae, the tavern cat. When a strange Murine fellow vanishes with a keg of the tavern finest, things really start to get strange.
The clock is ticking, and it is Last Call for our friend Oliviah!