There's Yer Problem

From the introduction: A powerful merchant has a “small” problem that requires some adventurers. It is a simple request — to enter the unique chambers under his mansion and help repair some machinery found there. The pay is good, the benefits are great, and helping a powerful merchant could lead to many rewards. However, nothing is ever as easy as advertised and the party finds themselves fighting creatures from the lower planes. What exactly is going on with this machine? User summary: For 2nd - 3rd level characters.