The Blasphemous Brewery of Pilz!

From the front cover:

Something has happened to the delicious beer in Shattenberg! None of the residents have seen the brewing monks for weeks and the tavern masters are oddly silent. Where once it was a delicious and creamy blend of mountain mushroom-based stout, it now offers an odd coppery taste and costs twice as much. For a small mining and farming town on the edge of the wilderness, this is a tragedy. Now rumors have begun circulating that hideous creatures gathered to the north are somehow the cause. The players are hired to investigate and, if possible, remedy the problem.