She was actually trying to shake things up a bit. Both her and the people she hung out with were social revolutionaries so there's a lot of anger in it and there's also a desire to change the world in the way we rely on the young to bring that fire to things.
There's a lot of that in Frankenstein and I hope it comes over in the play. Also, she was kind of breaking the model because no-one had ever written a book quite like this before so I hope the originality of it also comes over.
How does Shelley herself feature in the play?
RM: She's a character in it. If I said she was a narrator it would give the impression that it"s about storytelling but it"s a much more active role than that.
The book is all her voice, when you think about it. I've just put that voice on stage with her as a character so you see the story but you also see some of the emotional journey she went through to create it.
What was the inspiration behind that idea?
RM: Every version I've seen of Frankenstein becomes about Victor Frankenstein and the Creature so you have these two very iconic male protagonists.
It's been done as a metaphor for fathers and sons, everyone talks about Prometheus and the patriarchal God, Adam the man… The thing that seems to get completely obliterated is that this came from the mind of an 18-year-old woman and a very intelligent and talented one at that.
She went on to be a successful writer and she was probably responsible for preserving and even framing and amending the whole body of her husband Shelley's work so that we've got that too.
She's become completely invisible in the narrative of Frankenstein and even when she is credited with its creation it"s almost as if she did it organically or spontaneously, as if she didn't know what she was doing and it was just a mad dream.
As a writer, when you look at the book you go 'That is a very solid piece of storytelling by someone who is really skilled in structuring the narrative and putting it all together.'
That's not to say it isn't without its faults but then nothing is and when you think it was written by someone who was eighteen it's extraordinary. I just wanted to make that visible because I don't think it usually is.
Do you feel as a female writer, like Mary Shelley herself, that you bring a different take to the material?
RM: I think it's probably easier for me to imagine what it's like to be an 18-year-old woman trying to write your first novel.
I didn't do it as well as Mary Shelley when I attempted things like that and back when I started out things were considerably easier for women writers than they were for her.
But I certainly think it helps to have that memory of attempting similar things myself - and also being that little bit older and remembering when things were tougher for women writers, even if they weren't as tough as they were for Mary.
You've described the story as "the dark and rebellious roar of its adolescent author". Can you elaborate on that?
RM: She came from a group of people who were consciously thinking about how they could change the world in revolutionary ways and challenge the status quo.
It was partly out of the Romantic movement, which was a reaction to industrialisation and capitalism, and partly out of her own experience.
She was the daughter of Mary Wollstonecraft, who is pretty well regarded as being the first conscious feminist in as much as she articulated a lot of what has become contemporary feminism.
She wrote a book called A Vindication Of The Rights Of Woman and she was an active participant in the French Revolution, up until the point where that took a turn into violence and then she moved away from that.
And Shelley's father was the political philosopher William Godwin so it was all about 'Just because the rest of the world does things one way it doesn't mean that we should do that too' and constantly challenging the way society was developing.
With that behind her and the group of people she was hanging out with, I think she wanted to articulate some of that anger and frustration that the world was unfair - and particularly unfair to the poor and those who didn't have access to political power or wealth.
What's really interesting when you read the book is that some of it seems so contemporary and those are the bits that people tend to ignore because they don't fit with the kind of Hammer Horror view of it as just being a horror story about creating this monster.
The other sections of the book don't get a lot of attention but she's explicitly saying 'If you ignore the weak and the oppressed and you marginalise them then they will rise up'. There's a sense in which the monster represents that narrative.
In researching the piece, were there things you were surprised or intrigued to learn?
RM: The thing that surprised me the most - and I'm really ashamed I didn't know this - is that she lived into her 50s and wrote other novels which we don't know about, although they sold at the time, and that she sustained her whole family.
She lost three children and ended up being a single mother with one child to support.
She also supported various dependent relatives and friends and she did so through her writing.
She was a professional woman in the early 19th century who made a living out of writing and, as I say, she is also probably the reason that we have a large number of Shelley's poems because when he died young she inherited the estate.
A lot of his poems were just kind of scribbles and doodles so she pulled them together and gave them shape and form.
I had this vision of a kind of frightened Goth young woman in a white dress in a thunderstorm at Lake Geneva having hysterical dreams because that"s the way it had always been presented to me.
Then when you look into it you go: 'Blooming heck, this is someone who quite early on went "I've got make a living out of this and a good living out of it because I have no other means of making money".'
She'd been such a social revolutionary because her and Shelley had chosen to live outside society.
She wasn't getting any money from his family and her own family had kind of cast her off when she ran away.
She really needed to make a go of it as a writer and for me, knowing how hard that was in the 20th and 21st centuries, to do it back then was quite remarkable.
That was something I didn't know about her and it was quite chastening and also empowering to find that out.
Frankenstein aside, do you think she was underrated as a writer during her lifetime?
RM: I think she was always conscious that people wanted to know about Shelley and Byron and this book. It was her fame and it remained her fame. I think she was quite philosophical about that and used it when she needed to.
One of the things I'd like to do now is have a look at some of the other novels she wrote. I suspect they're not brilliant because otherwise we'd probably know about them but I bet they're better than we think they are.
Why do you think theatregoers enjoy a good scare?
RM: I think we enjoy it up to a point and where that is depends on the individual - and I've got a very low threshold for horror.
But why do we like it? I think it"s because life is terrifying, the imminent inevitability of death is terrifying and the fact we have no control over the bulk of what happens to us is terrifying too.
If was can find a way of expressing that terror which is manageable and controlled so we can have the sense of looking at it without it being just so gut-wrenchingly ghastly that we can"t bear it, then that is quite cathartic. That's what I think horror offers people.
The best horror stories tap into universal fears. What are the fears that Frankenstein stirs up?
RM: It's that thing of not being in control of your own fate. I think not being able to escape the consequences of your own actions is also a biggie.
That's where the horror of the monster comes from because basically at a certain point Frankenstein doesn"t take responsibility for his actions and from that point on there's no escape.
It's about relentless pursuit and you can have the illusion of escape but it always comes back to you.
That's a trope of so many horror films; just when you think it's all over the hand bursts out of the ground or the axe comes through the door.
Can you tease anything about how Frankenstein"s monster will be depicted?
RM: What I can tell you is that it won't be what people expect. After James Whale did the film in the 1930s with Boris Karloff the monster became this kind of sewn-together creature with bolts in his neck.
But if you read the description in the book there's no mention of him being sewn together and there's no description for how Frankenstein assembles the monster.
It suggests something much more chemical, almost as if he was boiling corpses down and reassembling the body matter.
It's really not clear and equally there"s no lightning to animate the monster. Again it suggests a much more chemical process with the implication that maybe electricity was used.
Our monster is not going to be sewn together from bits of people, he's not going to have a bolt in his neck and he's not going to be animated through lightning.
He'll look utterly terrifying but he won"t look like you expect.
RM: Can you recall when you first encountered the Frankenstein story and the effect it had on you?
I read it when I was quite young and I probably saw the films when I was a teenager.
The thing that vividly sticks with me, though, is that my son wasn't a big reader - which you can imagine being a shock to me as someone who deals in words.
I assumed he was going to be a reader but he's an artist actually.
When I was a kid I kept giving him book after book and he'd get into some of them, but he didn't really want to have his head in a book.
Then one day he came home from school and said 'We've got this set text and it's amazing'. It was Frankenstein and he pretty much read it over three days.
You look at how difficult that text is. It's not easy language and he was about 13 or 14 at the time but he gobbled it up.
That really stuck with me - that there's something in that story, probably because Mary was a teenager herself when she wrote it, that just grabs people of that age. I hope that"s something this production can do as well.
What else do you hope audiences will take away from seeing the play when they leave the theatre?
RM: I hope they'll realise that Mary Shelley wrote it and that they'll know a bit more about the person she was. I hope they'll be satisfyingly terrified.
And I hope people who have loved the story in other incarnations will think this is a great version to add to that canon.