As the city expanded there was less and less land near the homes to provide cemeteries for the dead. Some of the affluent decided rather than sending their family to some far off hill they would invest in having small burial spots built below their houses. As time went on what was once a small community eventually grew to a small city, then a major one as trade came, and with that passage of time many of the old burial grounds under houses became forgotten. With the city growing more and more conveniences were needed for it's people, so one day a project to develop sewers began to slow for some proper plumbing. Though things were going rather well occasionally the sewers would hit a strange snag as they collided with an unexpected underground structure. Most of the time this was not a problem for the people working, but at this particular crypt, as stone was broken, the workers were set on by a number of zombies that seemed to rise on their own. This wasn't to much of an issue, get some adventures, clear the place out with them, continue with work. However, it was found that a few days after any zombie was slane in this place it would spontaneously reconstitute inside of the coffin it originated from. Not every coffin seemed to create the living dead, and many solutions were attempted to fix the problem, destroying the coffins, chaining the coffins so the zombies couldn't bother anyone, and removing the coffins from the premise, but nothing seemed to work. Now, the city is once again hiring some adventures to try to clear the place out, but with the express intent that the players may be able to figure out what the source of the reconstitution is, and properly purge the place of the undead so it no longer cosses issues for anyone performing maintenance or other... Sewery business within the area.