Last year, Brian K. Vaughan and Marcos Martin announced that they would be making a one-off comic in The Walking Dead universe, as part of a deal between Image Comics and their comics distribution service Panel Syndicate. Now, you can read it — and it's got some pretty major implications for the comic series as a whole. The Walking Dead: The Alien is set in Barcelona in the earliest days of the zombie apocalypse. And this is actually the first official material in the comic series' long history that confirms it's not just America that's fallen to the virus. Rather, the whole world is in a similarly apocalyptic state.
The Alien goes far beyond just that, when it comes to tying in elements from Robert Kirkman and Charlie Adlard's iconic comic in some interesting, but spoilery ways, so I'll leave that for you to find out. Good news though! You can do so by heading on over to Panel Syndicate and paying whatever price you want to download a DRM-free version of the comic.