There are countless zombie narratives out there in film, TV, books and comics. Zombies are big business because they tap into a wide range of fears and anxieties. Many of these revolve around disease and contamination.

In recent years, for instance, the success of first world medicine has given rise to threatening ‘super bugs’ that can resist antibiotics. Writers use similar medical rationales to reinforce the zombie phenomenon in their fiction. These fit in with a scientific world order in which God is long dead, and religious or supernatural beliefs old-fashioned or obsolete for many.

Contamination fears in zombie fiction have also been linked to racial, sexual and class anxieties. For example, George A Romero’s cult classic The Night of the Living Dead has been connected to the trauma of the Vietnam War in the US, as well as the struggle for racial equality in the 1960s.

Concerns over our civility and morality are another central theme. The notion that humanity is tainted by its capacity to inflict terrible suffering has long been the source of fables dating back to The Brothers Grimm. This goes even further into our storytelling past – for example, the epic Beowulf dramatises the tension between humans and monsters where suspicions concerning the beast within us operate as a subtext. Old Testament Biblical tales also depict the painful truth of our violent nature. There are innumerable genres, including gothic, detective, horror, and fantasy, which each explore our shadowy existence.

The Walking Dead deftly examines humanity’s heart of darkness. It is not the zombies who are the ultimate villains – in some cases they are the victims of human sadism. Rather, it is the ruthless survivors of zombie attacks who pose the most threat. Once stripped of the basic comforts of clean water, food and shelter, the abyss of human cruelty is opened up, as well as other weaknesses. The main game – survival – involves compromise and violence. Those who refuse to shed blood are held in suspicion or die.

Jack London’s Call of the Wild adage ‘eat or be eaten’ encapsulates the attitudes of some of the survivors in The Walking Dead. The taboo of cannibalism is not limited to the zombies who feed upon human flesh. The great horror is that humans can be far more vicious and cunning than any other species, which is why we are the most dangerous animals on the planet. The Walking Dead cleverly plays on this point.

The conflict, initially between humans and zombies, becomes a battle between decency and depravity and the ever-shifting border between them. The central protagonist, Rick Grimes, represents a compromised civility. When he kills, he does so in self-defence, as well as for the good of his group. There is always a reason preventing him from descending into madness and chaos.

The future of humanity lies in the promise of Rick and his loyal band of followers. He is by no means perfect, but he is flawed enough to be likeable. The challenge for Rick and his PTSD-affected group of war-torn warriors is whether they can stop fighting long enough to forge a brave new world that goes beyond the limits of survival. Season five of the TV series leaves us wondering if this will happen.

Also typical of zombie narratives are their apocalyptic end-of-the-world milieus and attitudes. However, the environment of The Walking Dead is not so much apocalyptic as it is drenched in eternal terror and warfare.

Robert Kirkman and Tony Moore’s graphic comic books, dramatically realised in Frank Darabont’s TV series, depict endless scenes of violence in which zombies are bayoneted and shot in the brain. Repetition has a way of making this act palatable, even routine. In fact, Rick and his crew become so fatigued by the monotony of battle, that there is a need to introduce hostile survivors to reinvigorate the narrative.

It is also easy for audiences to become psychologically embroiled in the dark world of The Walking Dead, where the relentless conflict between zombies, vicious survivors and decent humans appears normal. This fiction has the capacity to impact upon our perception of reality, in which we become desensitised to the violence.

Binge-watching the TV series strangely parallels the hunger of zombies. Strangely again, The Walking Dead’s constant warfare echoes America’s persistent state of emergency ever since September 11. In a post-September 11 world, zombie narratives have become increasingly popular. Indeed, the comic book of The Walking Dead launched in 2003, barely two years after the terror attacks on US soil – perhaps a response to a world that has become more paranoid and brutal. Extending the analogy, when will the US cease its implacable military operations? As in The Walking Dead, it is apparent that both real and imagined threats to America’s homeland normalise feelings of justifiable self-defence. The CIA’s exposed torture methods are rationalised in such a way.

The Walking Dead provides unforgettable drama examining the depths of human vice and virtue. It also offers insights into the damage done to individuals, communities and entire nations when a perpetual state of war becomes a reality.