Nestled between the towering cliffs of the Zorian plateau, lies a vast cavity that is wide enough to swallow an adult bull elephant with enough space to spare for a small herd of draft horses on either side. There you will find gold, an abundance of it. But what is that you say? That the natives tell you that it is a place of death and home to hideous monster that will devour you? Ignore the savages. They only seek to protect what they are too indolent to grab for themselves.
-A Khanate offical assuring a bunch of miners.
The secret for immortality has been discovered by an eccentric wizard/mad scientist. Its found you need to reapply once a month. As people stop dying, and the birth rate increases exponentially, people are forced into homelessness, because of the need for food reamins the same, and food is not being produced fast enough to feed the undying population. The PCs have to find the creator and kill him, and destroy production, to save the world from undying, unending torture from hungryness.