one shot #2 exterminate rats

This will be a one shot to let the players know how it is to be villagers dealing with small pest problems will need 20 playable level 0 NPC and two threats that grow after every death. one will be kobolds raiding the feilds, and the other is rats out of hand in the basement of the inn.

Plot points/Scenes

the town is made up of 50 people, none of who possess a PC class. the first quest will be to clear out some rats.  to go for help will require the party to circumvent the kobolds in the valley that leads from their own town to the rest of the world. this will be almost impossible. 
the main event is that with every death the situation worsens. the kobolds reproduce. the bodies rot and turn undead. the rats reproduce adn infest other buildings