At Trinity College Dublin everyone wants to be Sally Rooney. The success of her novels Normal People and Conversations with Friends about students falling in and out of love at the university has inspired imitators. Lots of them. Dublin’s coffee shops and bars are packed with hunched proto-Rooneys clattering away at their laptops in a race to complete the next voice-of-a-generation bestseller. The Irish literary magazine The Stinging Fly is scoured suspiciously for signs of threatening new talent. Even conversation is self-consciously Rooney-esque: love, late capitalism, the moral sympathy of George Eliot.

This, at least, was the picture painted by Susie, the Trinity student who volunteered to show me around the university’s severely handsome 18th-century campus before it was closed down in mid-March because of the coronavirus. She gestured exuberantly at the courtyard in front of us and declared: “It’s an absolute phenomenon!”

It certainly looked that way. A herd of actors dressed as students (or, presumably, student actors dressed as students) trooped up the steps of the university’s colonnaded theatre to act out sitting exams. An enormous camera trundled urgently across the cobbles. Costume designers with their arms full of vintage clothes trotted in its wake. Filming for the BBC adaptation of Normal People, Rooney’s second novel, was in full swing.

It is the sort of book that until recently was thought extinct. An intelligent literary novel that topped the bestseller lists for months, earned a place on the Man Booker prize longlist and won the endorsement of the model Emily Ratajkowski as well as The New Yorker. It has pushed its way into the cultural mainstream in a way we thought only Netflix shows could nowadays.

Rooney’s novel concerns the on-off relationship between the formidably bright Connell and Marianne as they progress from their state school in rural Ireland to Trinity College Dublin. (British readers should think of Trinity as Ireland’s Oxbridge, but with an even more formidable reputation for privilege and private school-honed elitism.) At its heart Normal People is a sweet, even straightforward love story (speaking of her plots, Rooney says that her books have “19th-century engines”). But what got critics excited was her introspective, ironising prose, which seemed to capture a generational voice.

It is the sort of book that until recently was thought extinct. An intelligent literary novel that topped the bestseller lists for months and earned a place on the Man Booker prize longlist.

A TV adaptation was inevitable (an adaptation of Conversations with Friends is also in the works). It is directed by the award-winning indie film-maker Lenny Abrahamson and has a script (the book’s fans will be reassured to note) written by Rooney.

Abrahamson, 53, says that he was drawn to Rooney’s novel for the way it captures the “intensity” of university and coming of age. As an “older person”, he says, “that’s very easy to forget”. The book’s heartfelt and uncynical love story is “so hopeful” in “a culture where so many of the narratives about young people and sex and love are so dystopian and so problematised”.

It’s exactly this lack of fashionable posing and willingness to risk sentimentality that have won Rooney so many fans. As a director, Abrahamson says that the book’s short chapters and abrupt leaps through time presented interesting technical possibilities. Each of the 12 instalments lasts only half an hour (usually the length of a sitcom episode) meaning that the show progresses as a series of “short, intense bursts of a really compelling relationship”. Much like the book.

Sally Rooney, author of Normal People, a love story that unfolds against the backdrop of university life in Ireland.

Determinedly self-deprecating, Rooney habitually insists to her interviewers that the cultural position of novelists in the 21st century is marginal. But even she allows herself to sound awed by the process of creating the TV series, which she describes as “a combination of traumatising and so hugely rewarding my brain couldn’t process how exciting it was”.

At its heart Normal People is a sweet, even straightforward love story (speaking of her plots, Rooney says that her books have “19th-century engines”).

Typically, Rooney is overthinking the experience. Visiting the set of Marianne’s house gave her, she tells me, “the bizarre sense of walking through my own psychology … like I was physically walking through the projection of my own psychological state at the time I was working on the novel”. It is “surreal” to think “a huge team of people put together this psychological projection of mine that I came up with two years ago on my computer”.

That the set of Normal People gave Rooney the sensation of travelling through her mind is a testament to the fidelity of Abrahamson’s adaptation. Rooney nerds will be reassured to know that the show is packed with recognisable lines of dialogue from the books and countless moments that had me exclaiming things such as: “Ah, of course, that’s the bit where Marianne is sitting on the kitchen table eating a yoghurt discussing her exam results.”

Physically the novel’s protagonists are cast almost flawlessly. In the book sensitive Connell has a “hard-looking face, like an artist’s impression of a criminal”. And so the producers found Paul Mescal, 24, an unknown actor from Maynooth in Co Kildare, who, with his ever-so-slightly wonky nose and heavy brow, projects the appropriate air of shy, recidivist charm. Daisy Edgar-Jones, 21, who plays Marianne, looks not unlike Rooney and has such a convincing literary aura that when I bumped into her in Foyles bookshop a few weeks ago and found myself unable to place who she was (I’m terrible with faces) I assumed she must be a book reviewer I knew from somewhere. (Daisy, if you’re reading this, I apologise for the confused expression on my face for the duration of our conversation.)

Both actors are Rooney apostles. Mescal has read the book five times, refers to it unironically as “the bible” and described meeting Rooney as “daunting”. During filming he assiduously cross-referenced each scene to check what Rooney said Connell was thinking and feeling at that time. If his acting career doesn’t work out, the inevitable school of Sally Rooney studies at a richly endowed American college has its first lecturer.

Determinedly self-deprecating, Rooney habitually insists to her interviewers that the cultural position of novelists in the 21st century is marginal.

The actors studied the playlists that Rooney created for their characters while she was writing the novel (you can still find them on Spotify). Mescal says, with what Rooney’s fans will consider the appropriate level of awe, that “it’s romantic to think that she was listening to those songs while she was writing it and now we get the opportunity to listen to those songs while we were getting ready to play the parts”.

Endearingly, and with a note of self-deprecation that the author would approve of, Mescal and Edgar-Jones tell me that the greatest challenge of their parts was playing “such hyper-intelligent” characters. Edgar-Jones worked her way through every book Marianne is supposed to have read (which is a lot of books and includes at least the first volume of Proust), although she says that she struggled with Doris Lessing’s The Golden Notebook.

For all the Rooney-mania of the young cast members, Abrahamson and Rooney are keen to play down the idea that the TV show is the slave of the book. “Only a very, very small percentage of people have read my book or even know of its existence,” Rooney insists. That means the “TV show has to be its own thing and it has to function completely separately and exist on its own terms”. She’s concerned not to pander to the fans of the novel. “The people who read the novel — I’ve done enough for them. I did write a whole book,” she exclaims with mock exasperation.

That approach is a wise one. Abrahamson and Rooney know that an adaptation of a literary novel can’t satisfy the readers who loved the book for its style. No adaptation of London Fields could capture the hectic ambition of Martin Amis’s prose, no sane Middlemarch adaptation would bother trying to recreate Eliot’s long philosophical passages.

What got critics excited was her introspective, ironising prose, which seemed to capture a generational voice.

The problem is especially tough in the case of Normal People. Its principal stylistic characteristic is self-consciousness. The book runs on twin tracks: what the characters say out loud, and what they would have said out loud were they not too nervous or proud or lacking in self-insight. Rooney acknowledges that “the distance between those two things [the said and the unsaid] is to a large extent what the book is about”.

How do you adapt a book set half inside its characters’ heads? “Novels have the interior voice,” Abrahamson concedes, “but film has faces.” Rooney says that learning to become a screenwriter meant she had to chuck out half the items in her novelist “toolkit” and discover things such as “smiles and glances”. She’s very big on glances and refers to them so frequently in the course of our conversation (“I love the power of a glance”, “Glances are so important” etc) that I begin to fear that the show will be filled with characters goggling and leering at each other in desperate, stagey attempts to project their interiority. Happily this is not the case.

The adaptation is a touching reminder of how trivial many of the incidents in Rooney’s books are. Her writing is so concerned with the grand internal dramas of mind and heart that it’s easy to forget that the things her characters worry about in the early chapters (the social embarrassment of spilling yoghurt on yourself in the school canteen, not going to the prom) are merely the crises of everyday teenage life. Abrahamson also refuses to shy away from the sex scenes that, looking back at the book, are more explicit than I had remembered. As I watched the naked Marianne and Connell launch themselves into the throes of passion my flatmates were moved to inquire whether I really was “working from home”.

Abrahamson escapes the pull of teen drama banality with carefully rationed musical interventions (Nick Drake’s instrumental track Horn supplies timely magic in episode two) and, yes, a few well-judged glances. Marianne’s tender absorption in Connell’s slow-mo triumph on the school football pitch risks sentimentality, but Rooney’s willingness to take precisely that risk is the root of her novels’ success. I think the scene works.

Abrahamson tells me that making an adaptation “really tests a novel, because you just have to dig, dig, dig. Any flaws or cracks will be revealed.” In Normal People there are none, he says. I wouldn’t go that far. Although Rooney’s emotional insights and command of interior drama are delicately filamented, in the bright light of the TV cameras some of her characterisation is revealed as heavy-handed. You realise that her decision to have Connell’s mum work as a cleaner in Marianne’s enormous house lays the class symbolism on a bit thick. And I noticed that the TV version of Marianne’s villainous and bathetically named brother Alan is wisely toned down to evade the possibility of melodrama.

The business of literary adaptation is notoriously tricky. Normal People has some very enthusiastic, very wise people behind it. If it’s a success, perhaps even Rooney will be forced to concede that she’s no longer a marginal figure.

Normal People will begin streaming on Hulu on April 29, 2020