Last year the New York Times ran a quiz entitled “Could You Have Landed a Job at Vogue in the 90s?” It was based on the fabled four-page exam Anna Wintour had would-be assistants sit – a cultural literacy test containing questions about 178 notable people, places, books and films. I’m afraid that this former (British) Vogue intern did not pass muster: wrong era, wrong country.

A woman who almost certainly would pass with flying colours is the former Vogue staffer Caroline Palmer, now the author of a novel, Workhorse, set at “the magazine” during the dying days of a golden age of women’s glossies, when the lunches were boozy, the couture was free and almost anything could be expensed. In this first decade of the new millennium, we meet Clodagh, or Clo, a suburban twentysomething “workhorse” trying to make it in a world of rich, beautiful, well-connected “show horses”, and willing to do almost anything to get there.

The women’s magazine has an established literary history, from The Bell Jar to The Devil Wears Prada. So too does the genre we’ll call “young woman comes of age in New York City” – I’m thinking of books such as The Girls’ Guide to Hunting and Fishing, Rules of Civility and My Salinger Year. Then there’s the grifter narrative (The Talented Mr Ripley, Emma Cline’s The Guest, Gatsby, even Breakfast at Tiffany’s). The grifter isn’t solely an American phenomenon, but it makes the most sense there; a new country without an aristocracy, where reinvention always feels possible. Workhorse is a novel that ticks so many boxes it’s unsurprising that it provoked a bidding war. It even has that most fashionable of protagonists: a highly dislikable heroine.

Clo is a liar, a thief and an alcoholic who brims with class envy and internalised misogyny. The way she describes other women is often vile, though sometimes hilarious: “she looks particularly haggard tonight in the harsh kitchen lighting, like when you spot a famous actress buying bananas at a Midtown bodega”. It feels fitting for a character who finds herself in a working environment where people say things such as “there is nothing more disgusting than seeing a woman eat the appetisers at a cocktail party”. Despite Clo’s unpleasantness, as is the way with these novels, you cannot help but root for her – initially, at least. Workhorse follows her from her days as an underling to an Upper East Side apartment and a job as an editor. Watching her get there is, at times, tremendous fun. Palmer has a talent for wit, and Clo’s observations on the foibles of the fashion industry are razor-sharp. Her dark obsession with the beautiful, well-bred Davis Lawrence, a colleague at the magazine and the daughter of one of the most awful mothers I have ever encountered in fiction, is well drawn, as is her friend Harry, the real Holly Golightly of the story. Here are two people who ooze charisma, where the seething, grasping, increasingly desperate Clo has none.

That, ultimately, is the novel’s problem. It’s not that young women don’t deserve to be the subject of Goldfinch-length epics, and I have no childish aversion to unlikable characters. I did, though, perhaps wish I didn’t have to spend so much time with Clo. Workhorse comes in at more than 500 pages, which is a long time to be in anyone’s head. Perhaps it is an issue of the first person, and a close third person would have worked better. Regardless, you could have cut a full third of this novel and I don’t think it would have suffered for it. If anything, that would have allowed some of Palmer’s truly brilliant writing – such as her gorgeous description of a New York power cut – to further stand out.

That the fashion industry can be shallow and ruthless is news to no one. The Devil Wears Prada was published 22 years ago, and we are now in a post-Wintour era. It’s hard to know how interested the general reader will be in another nostalgic swansong for the heyday of magazine publishing. I enjoyed a glimpse at the glamour immensely, though it’s always, in a sensation familiar to all journalists, tinged with the feeling that you got into the game just as the party at Bungalow 8 was ending. What elevates Workhorse beyond its central theme is a more profound exploration of the emotional burden carried by the perpetual outsider; what a weight – and a waste – such an envy and ambition entails, how one day you turn around and find that you have “burn[ed] through an entire decade in a single night”. As one of the characters says: “you grow up with all these questions you really want answered … Am I going to get married? Or will I have kids or a good job or whatever, and then when you start to get the answers, it feels sad?”

• *Workhorse by Caroline Palmer is published by 4th Estate (£16.99). To support the Guardian, order your copy at guardianbookshop.com. Delivery charges may apply.