While transporting barrels of Trioxin 49 gas through the arizona desert to lukes base for storage, a military convoy gets caught in a monsoon. The driver isnt experienced in driving through monsoon conditions and ends up driving into a wash. One of the barrels comes loose and falls into the wash, to be washed away into the desert. Days later a old prospector named Cleetus "Cowboy" Wilkins comes across the barrel and decides to use it to make a BBQ which he would be able to sell. Once at his shack, he opens the barrel exposing himself to the trioxin gas and releases the contained animated corpse. The animated corpse attacks and kills cleetus and shambles off into the night towards the sleepy town of nowhere,arizona.
How to work the characters into this adventure seed :
The pc's are traveling across the united states on a greyhound bus and Nowhere is a schedualed stop - When the bus pulls into nowhere, the dead have taken over the town and the players have to find a way to escape the endless horde of the living dead.