What a cliche, anyways, I have many ideas in my but this one is easiest to make a plot of!

The story would take place in any Amercian city you desire (I´m not american so you choose) a zombie outbreak takes place not only in this specific city but also in others ( we will see why later). So our characters (that may or not know each other) first have to escape from the city and search for any place to hide, not even military bases are safe as this outbreak is a total chaos. maybe they join a bigger group? stay only the two? why are they even together?