On the way home from a screening at the Soho Hotel in London, I was accosted by an elderly man at a bus stop who told me he had been possessed for 44 years and asked me what I knew about it? Naturally, I didn't know much, but I talked with him, spent the next few minutes engaging, with him rather than my usual Londoner trick of staring off into the middle distance, nervously edging away, and looking at my phone/copy of the Evening Standard/nails.

Nothing bad happened. I went on my way, he went on his. But I wouldn't have done even that little if I hadn't just watched Crazyhead, the new genre series written by Howard Overman, the creator of Misfits, and it wasn't still spinning around my head. Here's the teaser.

It's a drama about a couple of demon hunters. But it is so much more – and it will mean so much more to so many people. Although it's airing in the UK on E4 in October, the same channel that aired Overman's Misfits, it's been instantly picked up by Netflix who will air it subsequently to that, for an international audience.

Crazyhead is funny. It is scary. It is scary funny and relishes in both embracing tropes and overturning them. But it also covers all sorts of interesting ground that the creators may not have even realised they were treading.

Cara Theobold – previously of Downton Abbey, plays Amy, a young woman in a dead end comfortable life, who has been treated for hallucinations. Coming off her drugs however, she begins to see them again. People who are burning inside.

Susan Wokoma – previously of Crashing, plays Raquel. Who has always seen these people, and knows them for what they are. Demons. And suddenly Amy has someone who believes her, who backs up her world view and, crazy as it all sounds, it all fits together, possibly for the first time.

This might be seen as an unhealthy, codependent relationship – if they weren't utterly right. Demons do walk the earth, travel from person to person and do very bad things. Oh, and at least one is high up within the psychiatric profession. This is clearly a touchy subject for E4, especially considering the name of the show, and when I asked about the mental health aspects of this show, I was told that the show is about battling inner demons, just externally. I think it's more than that, intended or not, it shows a world where people have different views of reality, that these views can be useful and valid as others and demonstrates a greater acceptance and understanding of mental diversity. As taboo as it is, our world, our culture, has been formed by people who saw things at odds with others, from William Blake to Vincent Van Gogh. The demon hunters may bot be a perfect analogy, but as far as I was concerned, mulling this all over as I was approached at the bus stop a couple of hours later, changed the way I reacted.

It's not every television programme that makes you a better person, but Crazyhead just did.

So these are our demon hunters, two very lonely who believed they were the only ones who saw the world the way they did, have found each other and are trying to make a difference. They are from very different worlds, but through circumstance are smashed together and find in each other the support and friendship they have both been yearning for their whole lives.

And they have friends. Well, Amy has friends. Raquel just has a brother, Tyler – who fancies Amy. Amy has a co-worker, Jake – who fancies Amy. And Amy has a flatmate, Suzanne – who fancies people she really shouldn't – and probably fancies Amy too. Just a bit. This focus on Amy might be a little overwhelming, if it wasn't for an absolutely bombastic performance of Raquel, who explodes onto the screen like – well – Nathan in Misfits., Like Rudy in Misfits, Like Cassaday in Preacher. And with just those kind of lines, filthy, horrible disgusting lines ready with gusto and sincerity that redeems them, she possesses the screen, and no one is going to exorcise that away.

Because Crazyhead also an utterly filthy show. Did you know you can tell someone's a demon by the temperature of their semen? That you can only exorcise someone after urinating on them first? And killing a demon outright means sticking a pole up their ass? Makes Buffy's stakes seem rather… impotent.

But it's all a front, there are secrets to be hidden, there is a past with a not-all-bad demon who is definitely not Raquel's friend, but is an enemy to the other demons. Raquel… has an Angel. Or, rather, she did. She may, quite literally, say "I am a strong, black woman" and ready to pour hatred and filth in deserving directions, but she is compensating for a time where she was alone, scared and – it seems – betrayed.

The comparisons are there, with Buffy – and Angel. The PR does it from the get go, the trailer beginning with the line about how one in every generation is chosen… But, as Overman says, that was a long time ago, the current audience probably hasn't seen it and, frankly, it feels like a very different show.

But it is the kind of show that fanbases are made for. It gives agency, representation and iconic portrayal to groups of people who, frankly just don't have them. A genre show with a powerful black female not-thin lead, with a history of mental diversity? But in no way ever feeling anything like some kind of token casting, and rejecting any kind of "political correctness" with its language? I can see the fan art, the cosplay, the Tumblr posts, the shipping with Amy, and the screams of six thousand people in Hall H or Ballroom 20 next San Diego Comic Con. This show is made for that and, for once the Americans are going to get a hold of it very easily indeed, as it airs on Netflix as soon as the series has finished in the UK on E4.

America is also, of course, the very thing that destroyed Misfits. The show was so highly regarded that its actors were just picked off for movies and TV shows and the churn hurt the show. Overman talked about constantly getting calls from American producers and casting asking about the actors he worked with, to his irritation. But on Crazyhead, the main actors have been optioned for future seasons, a rarity for British television, but a modern necessity, it seems.

That's if Overman remembers who they are of course. I asked Lewis Reeves and Rian Steele who played Jake and Suzanne about how it compared working with Howard on Misfits where they had minor roles, to the much meatier parts in Crazyhead – and Howard was astounded to discover they were both on Misfits. He had no idea, despite casting them in Crazyhead.

So what else did I learn? That Rianne almost suffocated while making the show, when her breathing hole was covered with a leaf when being buried. That Susan can't actually drive, and her car scenes were all green screened – but when filming started, she'd never actually sat in the driver's seat of a car and didn't know where anything was – so Cara had to keep grabbing her hand to help her change gear for the camera.

Then there's the sound. From the opportune music (even if Burt Bacharach's people said no to the urination scene) to the slight breaths from Amy in the bowling alley – to the bowling ball giving me tricycle flashbacks to The Shining, it sounds wonderful.

The visuals are also a step up for Overman's productions, they have more money than Misfits and better technology, which makes for decent CGI-edited demon faces. There are beautiful touches throughout – the standout moment for me is when Amy confronts a suspected demon in a car park, walking around, unable to see him, there are prominent crosses in the background, it feels like a religious war is just beginning. And the use of actual rubber masks that contrast with the demon masks in an attractively mundane way – even if, as Raquel tells us, they smell of balls. "Rubbery balls."

Oh and, at the screening, we learned where the whole Crazyhead story began in Overman's head. When watching a female cyclist being letched after by a man on the street, shouting out "lucky saddle!" As the cyclist dismounted, and detached the saddle from the bike (for security reasons), ignoring the man, he had a vision of her taking that saddle and bashing the guy's head in.

This merged with another script he had planned, a father wearing a World's Best Dad shirt stalking his daughter through a house, the idea of being hunted by someone you know, love and trust, being the scariest thing going.

Crazyhead came from there.

One of the takes I had from watching was the idea that strange men, unknown men, can be potentially scary to women – and how well do we know anyone anyway. Just… because… you never know. This reading was something Overman rejected, but it seems pretty on the surface in the origins of the idea. Overman has a history of backing into socially relevant aspects with his work in an unintended fashion – Misfits was never meant to have themes about the empowering of an underclass, but it managed anyway.

In Crazyhead, the demons are men – white men in positions of power. If you could move from body to body, it might make a lot of sense that demons would gravitate to those identities in order to do better in this world. But it also emphasises all manner of social ills, making subtext into text like great genre shows do.

And this, from the first episode and a preview of the second, is exactly that. Which meant, after the screening, I had to do the kind of thing, I never ever do.

Sorry, Cara and Susan. Something just possessed me.

Crazyhead airs on E4 in the UK in October, and will be available on Netflix later this year.