"How is he? Will my son ever recover from the bugs that turned his brain to mush?"
The doctor pointed to where the thirty-seven year old was playing with toys on the floor. "It's been five years now and he has the brain of a child, give it another five and we can start the basics of teaching him magic again. He knows who you are but...but he will never have the same personality again, and by the time he regains all his magic skills at their former levels he will be in his sixties."
And in the name of the great and powerful I command thee to return to your body, hearth and soul, so that you might walk again and continue in the gods plans.
See that. . . wait. . . what!?! NO! I knew it was too risky here. You have brought ruin to us all. Why you ask? Ready your weapon, a traveler has come.
-Father Hayden, performing a ritual on the deceased outside the protection of the church.
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.