After a horde of 17 million viewers tuned in to see the season seven premier of The Walking Dead, it’s safe to say that this show is one of the biggest phenomena in recent memory. From season three onwards, this adaption of a relatively successful comic series has been the most watched show in television cable history, typically drawing in tens of millions in the US alone with each episode. But what is it about this zombie-bonanza that has infected people worldwide?

First, an introduction to the show itself. Meet Rick Grimes, former Atlanta Sheriff who awakens from a month-long coma to a world that has been overrun by the reanimated dead. Dubbed ‘walkers’ (the ‘z’ word is never uttered), these roaming hunks of decaying flesh are the fate that awaits any living human who is bitten by them. After stumbling out into the Atlanta countryside, Rick reunites with his wife Lori, his son Carl and a handful of other survivors who have banded together to try and rebuild some form of society amidst the ruins of civilisation. For over six seasons now, Rick and a rotating cast of characters have moved from place to place contending with walkers, the elements and worst of all, other humans.

On a surface level, The Walking Dead can comfortably be pigeonholed as a horror/post-apocalyptic series. Which, if true, makes the show’s success all the more baffling. Are families really getting together on the couch each Sunday night to watch a zombie’s head get smashed in? The likelier alternative is that The Walking Dead is not actually a horror series. While zombies are integral to the premise and no episode has gone by without some ghastly gore, the show’s longevity is actually rooted in something far more universal- its characters.

In many ways The Walking Dead is even a soap opera. Think about it: a drama that follows the daily troubles of an intimate community with no narrative end in sight. People tune in every week to discover what has happened to their favourite characters, and then avidly discuss it while eagerly waiting for the next episode. Even the creators and AMC have not been coy about their dream to keep the dead walking indefinitely into the future.

The Walking Dead may not appear as a soap opera in the traditional sense, but the universal appeal of the genre that the show’s creators have tapped into is undeniable. The focus is on people – Rick, Carl, Daryl, Carol and so many others. Zombies are just the window dressing. And that is a premise that appeals to a far wider demographic than simply horror fans, as well as helping to explain why so many people tune in weekly to see someone’s brains getting splattered with a baseball bat.

But outside of that appeal, it helps that The Walking Dead is also a bloody good show. Every single season is certified fresh on Rotten Tomatoes, and out of a total 84 episode to date, only nine are considered rotten by critics. The show is not without its rough patches – it is impossible to keep quality consistent over six seasons – but the overwhelming consensus is that it is good. Really good.

So where are the dead planning to walk to after the solid season seven opener? Odds are it is going to involve plenty of drama, a lot of gore and a few shocking twists to keep things interesting. And if the series creators have their way, The Walking Dead will to be shambling around long after we are six feet under.