Tilverton Tunnels

From the introduction:

The nobles in the upper sector of Tivlerton have barracaded themselves inside due to a plauge ravaging the lower city. The nobles believed that by walling themselves up they could escape the plague. Unfortunately the plague did get into the noble's sector and is ravaging the population. The nobles believe that they are safe and immortal but that is a sympton of the plague. The PCs have a cure for the plague but they cannot get into the sector easily to administer it, and even then they will need to be able to convince the nobles to take it. There is a way into the upper sector, but it involves travelling through the cities notorious sewers.