Howard Overman is the man behind E4's hit sci-fi comedy drama Misfits. Now he's back with a new show and explains all below.

What is Crazyhead about, how would you describe it?

Crazyhead is a genre mash-up with elements of horror, which is quite tongue-in-cheek, and a large dose of humour. It's principally about two girls who realise that the demons and scary figures they've been seeing aren't figments of their imagination, they are in fact real. And they become a sort of kick-ass demon-fighting duo, and go on a journey together. It's as much about their friendship as the genre elements, about two slightly lost girls who find each other.

Where did the idea come from?

There's that phrase that people have, 'battling your demons'. So I had this idea that these girls were both battling their demons in friendship and love and all the sort of messed up shit you have to deal with in life, as well as actual demons. Demon mythology is steeped in all sorts of cultures, from shamans to those people who can communicate with the spirit world. The idea that there's an evil out there lurking speaks to all of us and that's what the horror genre plays on, this idea of a demonic force. We liked the idea that it expresses itself in possessing people that you have a relationship with or are close to. It's more scary and intimate and bold if someone you thought you knew suddenly turns on you.

As with Misfits you have this extraordinary world imposed on ordinary life, is that where you like to start from?

It's something that's always appealed to me, this idea of crazy, extreme things happening but making them feel weirdly grounded and real. I think that's the trick in a way - making the genre stuff happen in a space where people can connect with it. I always try and write stuff that speaks to people who don't necessarily always watch genre shows, there's other things like life and relationships and finding yourself in there. I suppose the shows I enjoy have the element of suspension of disbelief but you feel like this could be happening in the room next to you. It goes back to something like Shaun Of The Dead, which made a zombie apocalypse feel grounded and real, and based in a reality you recognise.

Were your demon hunters always going to be girls?

When I first set out I always try and avoid having very set ideas, I'm not very prescriptive and just see how it develops. But these characters were always girls. There was something about the character of Raquel, about taking the archetype of a kick-ass female warrior and making her funny. I hadn't written that sort of character before. Quite often those sorts of characters can be quite dark, and I just wanted to write someone funny, heroic, kick-ass. Quite often they're not written, those sorts of parts for young women.

Raquel and Amy have been misunderstood since they were young, how does this affect their characters?

Raquel and Amy have both grown up being outsiders to a certain degree, and unsure of themselves and what they can see, and having this nagging feeling they're different to other people. Everyone wants to fit in, and if you don't, for whatever reason that is, life can be difficult. Outsiders saying extraordinary things, or people who see the world in different ways, are often considered freaks until they're proven right.

Their friendship and how it develops is at the heart of the series, are there any particular on-screen duos that influenced their characters?

The tropes of the buddy duos have been well trodden in film and TV and it's just something that works. If you look back at the history of comedy and drama there's something about having a straight man/funny man, or woman. You've got someone to talk to, to tell how you're feeling, and explain what's going on, and that's why the duo is such a key part of drama. Whether that's Breaking Bad or Cagney and Lacey or whoever. Laurel & Hardy - straight man, funny man, it's just a sort of key part of comedy. We come into the Crazyhead world through Amy and see it through her eyes, and with her we meet this outlandish figure of Raquel. Amy acts as our guide, and asks the questions we would naturally ask. Hopefully Amy falls in love with Raquel, and hopefully the audience will as well.

What can you tell us about Amy and Raquel's arch-nemesis, Callum?

These sorts of shows need a big bad, I like to think Callum's an original take on it in a sense. He's sophisticated; he loves the finer things in life, good food, nice cars, fine wine. Even though he's trying to destroy the world, he wants it done with a certain style and panache and takes the organization side of it really seriously. He's a metrosexual baddie who likes huevos rancheros for breakfast and who'd make the tortillas fresh. He's a proud man. Things have to be done with a certain style and competence and he gets very angry when they're not.

How much did you research the mythology of demons and the underworld?

One thing we didn't want to do with this show is over-complicate the mythology. You want to keep it simple. We didn't want this to be steeped in detailed Latin about this type of demon or that type of demon. Although the demons are a big part of the show it doesn't operate where there's a lot of talk - once you set out the basic world and premise you could disappear down a genre wormhole trying to explain everything. So we stuck to basic, classic rules about demons and possession - when you die they move on, they come from the underworld, there's certain ways you send them back. Just keep it simple and have fun with it, do a more comedic and original take in it without being bogged down in exposition. Classic rules to fit the tone of our show.

The obvious immediate comparison may be Buffy The Vampire Slayer, is that something you were aware of, and is it a fair comparison?

Obviously I watched Buffy. I'd like to think it operates in the same genre as Buffy but the stories and the characters are totally different as well as the tone of it - more irreverent, scarier. But you can't run away from the fact when you're making a show like this there has been other shows made in those genres. You'd be lying if you said they didn't influence you in some way. Buffy was written a long time ago now and it definitely paved the way for those sort of shows.

It feels like demons are having a bit of a moment on screen?

I don't know why you don't see a show for ages then suddenly a few come along at once - is it zeitgeist or is it just there's so many shows now? There's only a limited number of genres, inevitably there's going to be crossover. We're all influenced by genres that have existed over the years. Suddenly you'll get three asteroids-hitting-earth movies on the trot - maybe someone reads the same article in the newspaper, who knows. If you look at genres like medicine or crime there's so many at any one time, if you operate in less common genres and there's two of them at one time people go 'oh look!'

Raquel and Amy have some inventive methods to tackle the demons, are they from demon folklore or Howard Overman?

It's taking facts of the genre and subverting it a bit, and not taking it too seriously. When Raquel talks about poles up arses it's a metaphor for taking out the demons. She doesn't really mean it. We do find out whether or not that is a factual way to send a demon back to the underworld, or it's just a figure of speech. All will be revealed.