From the introduction:
This is a Middenheim adventure for first career characters. This adventure may be moved to any other town or city that can boast breweries, criminals, Halflings, Chaos magic, and dead people. If you can’t find all that there, you must not be in the Empire. It concerns the hidden treasures of a deceased Halfling brewer, alchemist, and lover.
This adventure takes place in Middenheim not long after the siege during the Storm of Chaos. While the city survived, many of its inhabitants did not. Ashes of Middenheim has a wealth of information about this city. While it is very helpful, it is not necessary to run this adventure.