((You can start pretty much anywhere you like, though you could be getting chased by some mutated creatures or be found cowering somewhere near the mall if you like, that would make it easier to introduce your character to the others, that or you might already be hiding in the radiation shelter before anyone else arrived, which means Camille and Liandra would be the first to find you.  The choice is entirely up to you where you want to start and how to enter the story, I'm just giving suggestions.))