There is just no killing the zombie. They groan from books, lurch from cinemas and feast upon the flesh of television once again. Where vampires once ruled, the zombie hoard now shuffles ever onwards. The Walking Dead, now nearing the end of its third series on Fox in the UK, is currently leading the pack, but BBC3, having just bid farwell to one supernatural drama, follows up its much-mourned The Fades on Sunday with new zombie show In the Flesh.

The appeal of zombies to drama-makers rests in their capacity to reflect human nature in extreme situations – and it doesn't get much more desperate than fighting for survival against the undead. As explored in stories such as 28 Days Later and Max Brooks' book World War Z, the real horror isn't the monsters but those fighting against them, and their descent into becoming monsters themselves. The best use of zombies, as is true of most supernatural elements, is when they're a part of the tale rather than the whole story.

In the Flesh's writer Dominic Mitchell knows this all too well. Just as Toby Whithouse's Being Human was originally about throwing different people together in a flatshare, Mitchell's drama started life as a tale about stigma and prejudice focused on a young man with mental illness who moved back home after violently attacking someone. The writer changed tack in the hope that a more fantastical vehicle would allow him to discuss themes in a looser way. Now, set in the fictional village of Roarton in the aftermath of a zombie apocalypse, In The Flesh follows the story of medically reformed "rotter", Kieren Walker, and his reintegration into a family that had lost him to suicide, and a local community of xenophobic curtain twitchers. Deadly serious in its execution, the show unfolds in the style of a conventional domestic drama.

"When watching movies, I always felt bad for the zombies," Mitchell says. "These living humans are killing them in such a macho, gleeful way and I was just like: 'You know, these zombies are someone's son, someone's daughter, someone's mother and father …' I wanted to ground it in that kind of realism – in what would happen if a zombie apocalypse happened in England for real."

By taking such a serious approach in empathising with the undead, Mitchell is able to ask questions most dramas cannot – exploring prejudice, redemption and the deep pain of grief. In one scene, for instance, Kieran's zombie-hating sister, talking to her brother for the first time since his suicide, breaks down in tears as she reminds him: "You didn't even leave a note."

Mitchell poses the question: "Maybe they ate our neighbours' brains or one of our families' brains, but they're better now because they take medication to control it. How do you come to terms with that?" The writer says he spent time thinking about attitudes towards mental illness and those who have committed serious crimes when writing. "There's an uneasy parallel and, for some, there's no grey area. As members of the Human Volunteer Force [those who fought zombies during the war] say: 'Drugs or no drugs, a rotter is a rotter.'"

That the genre can still evolve, even in a time of zombie saturation, possibly explains why this particular brand of the undead thrives while the vampire begins to burn. While shows such as Buffy, True Blood and Being Human have shown vampires are fully capable of tackling intelligent, human themes, there seems to be a limit to just how far they can stretch and adapt in a time of Twilight-induced sexualisation and overkill. The blank canvas of zombies, unlike the detached, constrained vampire however, doesn't suffer from such limitations.

As Mitchell says: "Every angle [from which] you could possibly approach the vampire myth has been told and I don't think that's the case with the zombie genre. Not yet anyway. As long as there's humanity, there's still new landscapes for story tellers to explore."