Andrew Davies is notorious for spicing up novels when he adapts them for television. He has scandalised literary purists by adding unforeseen raunchiness to everything from Northanger Abbey to Pride and Prejudice. Even now, very few of us can think of the scene Davies invented in which Mr Darcy (Colin Firth) emerges from the lake as the winner of the annual Pemberley Wet Frilly Shirt Competition without swooning.
But at last, Davies has found a book that requires no raciness to be injected whatsoever. He has transposed Joanna Briscoe's erotically loaded 2005 book, Sleep With Me, into a new one-off drama for ITV1 – and he didn't have to embellish it one little bit.
The novel's plot – about an obsessive love triangle between Richard (played in the film by Adrian Lester) and Lelia (Jodhi May), an apparently devoted married couple, and Sylvie (Anamaria Marinca), a mysterious French stranger, who messes with both their minds – is already quite erotic enough, thank you very much. Briscoe laughs that, "this is one book that Andrew didn't have to sex up at all!"
Funnily enough, while Sleep With Me has a very steamy title and crackles with pent-up sexual desire, it actually contains very little of what the red tops are wont to call "romping." As both Richard and Lelia become increasingly fixated by the enigmatic Sylvie, it's all about the promise rather than the performance of sex. It discusses the act, as opposed to depicting it.
Briscoe, 49, who picked up the Betty Trask Award in 1994 for her first novel, Mothers and Other Lovers, avers that, "Sleep With Me is in fact quite restrained. It's more about sexual yearning than shagging. Sylvie keeps Richard waiting for full sex – which only makes him want her more. It may have a sexy title, but I don't think Middle England will be outraged."
Davies explains why on this occasion he resisted his usual impulse to ramp up the erotic element. "Joanna deals with sex wonderfully," says the writer. "I wanted to realise faithfully these very erotic, but subtle scenes she'd written – I couldn't improve on them. Will it still be raunchy? Oh yes, although everything one does is within agreed limits. I didn't push it." Surely, that must be a first!
The denial of sex can often be more erotically piquant than the act itself. The 73-year-old Davies, whose CV also includes Little Dorrit, Bleak House, Sense and Sensibility, Brideshead Revisited and Tipping the Velvet, reckons that, "Richard and Sylvie's relationship is all about control and permission."
The fact that Sylvie appears so blank actually makes her more dangerous. It's seduction by stealth. Richard's infatuation with her sneaks up on him. He recalls that when he first met the elusive Frenchwoman at a party, "I was barely aware of her. At first glance, she was just a blur, a slick of grey nothing. Beware of mice." As in Jane Austen, much significance is invested in the tiniest gestures. Whether or not Richard will touch Sylvie's hand in a coffee shop becomes hugely important.
Davies takes up the theme. "Even though Sylvie seems so passive and demure, she's actually very much in charge. Her relationship with Richard is all about domination and submission. She dominates and he submits. She says, 'you mustn't move. I make all the moves. If you disobey, I'll bite you'. That's the sort of highly charged game she plays."
Briscoe outlines why she believes people are so drawn to Sylvie. "What do people find magnetic about her? It creeps up on them, and then they've no idea what has hit them. It's underplayed, but that level of subtlety can be very seductive. You think that you alone have discovered it, but far from it. A few people I've met have that quality, and it can very dangerous. People have said to me time and again, 'I know a Sylvie'."
The novelist also demonstrates a rare understanding of the male psyche in Sleep with Me – something that also impressed Davies. "Joanna's very good at putting herself into the mind of men," he says. "When Richard becomes besotted by Sylvie, he has no idea what's being done to him.
"He's utterly in thrall to this seemingly colourless little woman. He falls victim to blind helplessness and is being led by his groin to his doom. I'm sure a lot of us have been there at one time or another, and I'm sure a lot of us will recognise that."
Sylvie certainly uses sophisticated wiles to manipulate her lovers. It is those power games that make this essentially a work about the mind, not the body. Lester, 41, who is currently starring in Cat on a Hot Tin Roof in London's West End, says: "Sleep With Me is not about raunchy sex. It's about what people do to each other emotionally in relationships. It's a question of 'what do you really mean by that?'
"It's a psychological drama – thank God. I can act my way through that, rather than getting to a scene and thinking, 'oh no, I didn't do enough sit-ups yesterday.' Sex scenes can be very hard to film because sometimes all you feel is embarrassed for yourself and for the other actor. But this is not like working on The Secret Diary of a Call Girl – ruddy hell, those actors are brave! Here we're asked to convey emotion in a scene. It's much more satisfying."
Marinca concurs. "Sleep With Me is sensual, rather than sexual," says the actress, previously best known for her Bafta award-winning role as a kidnapped eastern European prostitute in C4's serial Sex Traffic. "There are no full-on sex scenes. It's not about revealing. It's about concealing – and that's much more interesting. The situations in this drama are uncomfortable, but that's the point."
The 31-year Romanian admits that these sexually explosive scenes are, "always difficult to film. But as an actress, you're trained to be able to forget about yourself and create another reality. That's how you can go home to your family at the end of the day." The ability to role-play undoubtedly comes in handy when you're taking on a character as devious as Sylvie.
So how does Briscoe manage to conjure up this twisted world of sexual intrigue? "Perhaps it's to do with the solitary nature of being a writer," she ventures. "You spend so many long hours on your own in the library, that if you can have this enticing world going on in your head, so much the better. That was delicately put, wasn't it?"
Sleep With Me occupies dark and brooding territory. It is leagues away from the sunny uplands of most ITV1 drama. Heartbeat, it is not. But Davies is delighted that ITV1 has had the courage to take a chance with this more challenging piece. "I saw some of the early cuts of Sleep With Me and thought, 'Goodness, this is not like anything I've seen before on ITV1'. It's conceptually very bold.
"ITV1 go in for all sorts of kinky sex murders in their dramas, but they are always sanitised by the presence of a detective, a good guy who makes it all OK. This is not exactly extreme, but it feels like a good little French movie. I think it'll really appeal to viewers who like that sort of thing. It'll also strike a chord with the people who like domination and submission." A mischievous grin spreads across Davies' face. "I mean, who doesn't like domination and submission?"
'Sleep with Me' is at 9pm on ITV1 on Thursday 31 December