The talk of this year’s London Book Fair, Esposito, 32, was signed up by Michael Joseph — Penguin Random House’s commercial fiction imprint — in a pre-emptive deal. With foreign rights sold in 15 territories and the film rights already with Fifty Shades producer Michael de Luca at Universal Studios, the trilogy is already worth more than £2 million, with the potential to make a great deal more, for everyone involved. And this before a single word has even been printed. The first of the three books, Mad, isn’t due out until June 2017 and Esposito is currently writing the film’s screenplay. Like EL James and Fifty Shades, she’s keen to own the rights to the film as well as the book and hopes Jennifer Lawrence or Emma Stone may play her “Iago with tits”.

The clamour for Mad, Bad and Dangerous to Know began last June, as Esposito was finishing a six-month writing course at the Faber Academy in Bloomsbury, having given up her job as a management consultant. The £4,000 course, which has produced a steady stream of published authors including SJ Watson, Rachel Joyce, Joanna Cannon and Renée Knight, holds regular agents’ days, when up to 50 agents come to hear the Faber Academy “graduates” reading their work for two minutes. “I read the opening of my novel and after that it just went nuts. I had a queue of agents waiting to talk to me and 21 offering me representation.” She eventually chose Simon Trewin at William Morris Endeavor,

“I loved him straight away, and WME is such an amazing agency too because in the back of my head I always wanted it to be a film, and they have strong LA links with the film industry.”
For his part, Trewin is understandably delighted to be representing what he calls “an instantly gripping” story with “a voice that appeals to me”. The money must be appealing too. “The money is interesting, only in as much as it demonstrates a couple of things about publishing at the moment. Publishers want to put a lot of passion and resource behind something, so the money represents money, yes, but also momentum and energy, and it means the publishers will promote the hell out of it,” comes Trewin’s reply. “I read lots of unpublished material, and a lot of it is clearly someone analysing last year’s successes and writing a pale imitation of EL James. There’s a Venn diagram with an overlap of different genres but right in the middle it’s just you [Esposito].”

The funny thing is that if you were cynical enough to draw a Venn diagram and put chick-lit, chick-noir and clit-lit in your circles, you might just come up with a new sub-genre, clit-noir, as it were, which is precisely what this is.
So what’s the sell? “The story is about the lengths an identical twin will go to, to steal her sister’s perfect life and keep on living it. The sister lives in Taormina in Sicily. It’s glamorous and gorgeous and she’s got this stunning villa, sexy husband and beautiful baby boy, while the evil twin is this badass anti-heroine, the naughtiest person I could possibly imagine,” says Esposito, nervously crossing and uncrossing her legs. This is her first full-length interview since her whirlwind success began six weeks ago and she gives the impression that her feet still haven’t touched the ground. What sort of naughty? “The sky’s the limit! That’s why it’s rated 18. It’s completely immoral too, with jealousy being the main theme of the novel and her motivation.”

It sounds a bit like Gone Girl, I suggest. “I was so inspired by Amy Dunne from Gone Girl and I’ve read a few interviews with Flynn where she talks about how women can be as evil as men and I buy that. You’ve got some great evil women in the history of literature too: Lady Macbeth and Tamara from Titus Andronicus in Shakespeare. So often the man is the evil, ass-kicking, gun-wielding bad boy and the women are the moral characters, but it doesn’t have to be like that.”

Esposito, who grew up in Cheltenham and read English at Oxford, cites Bridget Jones “gone bad” as another big influence. “My character, Alvie, is 26, a relatable London girl, normal- looking but scrubs up well, and works as a classified advertising sales rep, cold-calling for hair regrowth supplements and Viagra for women or whatever. She drinks too much, she smokes too much and she’s a party girl.”
And she has sex — lots of it. “It’s hot, it’s explicit, it’s like fantasy stuff. It was so much fun to write. My girlfriends and I drank wine and sat around editing the sex scenes to make them even hotter and we had a great time.”

Comparisons with Fifty Shades are inevitable. “It’s a very different take on sex.” Esposito argues. “My protagonist goes on top and doesn’t take any bullshit like Anastasia Steele. She’s highly promiscuous. She’s slept with 303 men (in eight years) and she gets what she wants sexually without having to be tied up.” What did she make of EL James’s erotic trilogy? “To be honest I only read half of the first one so I can’t really comment. I do still need to read the other ones but I’ve been busy writing my own stuff.
I really admire Erica and what she did and how it was obviously hugely popular and what people wanted to read. It’s a brilliant achievement. I don’t know if I’m the target reader of those books; I’m a writer myself,” she replies.

For her part, she says, the book is “a feminist statement” about empowerment and she has been delighted by her publisher’s response. “Penguin had a launch party with 40 people and some of the younger women who’d read it said afterwards that they just didn’t load the dishwasher because it was their boyfriend’s turn, which made me really happy.” Her Roman hedge-fund husband, Paolo, hasn’t made it to the final page yet. “He’s been listening to me airing ideas about it for about a year but he’s only read a little bit of the novel because he’s not a reader. He works in finance and hasn’t read a novel since I met him 10 years ago.” How will he react to the sex scenes? “He’ll probably throw me straight into bed,” Esposito giggles, “although that’s not why I wrote it. I wrote if for my own entertainment.”