This is a great, fun little short story. An interesting twist on the zombie genre, which I'm very familiar with in films but have never read a zombie book. Good descriptions of Mars' tunnels and towns - reminiscent of Total Recall a bit (that's a good thing!). Well paced and some nice dialogue.
Quite short but very well written. Edward W. Robertson is now one of my favourite authors. Over the last month I've downloaded and read everything he's published. You won't regret buying any of his work.