Adapting much-loved books for the screen is risky and can be fraught, especially if a series has been as adored as Elena Ferrante’s Neapolitan novels. The characters live so vividly in readers’ minds that their TV forms may only be able to exist on a sliding scale of disappointment.

Thankfully, Saverio Costanza’s take on the first instalment, 2012’s My Brilliant Friend (Sky Atlantic), comes with an understated, solid confidence that suits its source material perfectly. Ferrante, whoever she may be, is credited as one of four writers on the show, so it is little wonder that it feels authentic, but this is a gorgeous TV show on its own merits.

It is unlikely that anyone who read the novels would expect a boisterous affair, but, even so, the first episode (of eight) unravels at a notably unhurried pace. This languid approach may be a turn-off for some, but it has a steady-handed charm. By the end of the first hour, we know Lenù and Lila as if we are close friends. Perhaps more perilous than trampling over beloved stories is relying on child actors to carry them, as is necessary in episode one, but Elisa del Genio, as Lenù, and Ludovica Nasti, as Lila, are remarkable. As fights and disagreements rise and fall around the girls, Costanza’s direction lingers on their expressive faces; the arduous casting process, which reportedly took months, was clearly worth it.

For those who have not read Ferrante’s novels – nobody should have trouble getting into the TV series, regardless of whether they have or not – the story begins when Elena (Lenù), at this point in her 60s, receives a phone call from the son of her childhood friend Lila. Lila is missing; she has taken her clothes with her and has cut up family photographs. Elena’s response is muted and eventually cold, teasing of a long and complicated past. “Learn to live on your own,” she advises him, suggesting she is unlikely to win an award for compassion any time soon: “And don’t call me again, either.”

It is in the past that My Brilliant Friend lives and breathes, however. The first episode unfurls around the ways in which Lila and Lenù became friends. They live in a poor Neapolitan neighbourhood after the second world war and meet in school, cautiously aware of each other, but yet to make the approach. Lila is the girl everyone avoids, warily testing the boundaries of her ferocious intelligence as she hides behind dirty hair and a tough attitude. Lenù works and grafts to keep up with her, fascinated by the only girl in the class who seems to match her appetite for discovery. Neither girl is the kind to look away, from dead bodies or dark staircases. Through their eyes, we discover the intensity of friendship, as well as the secrets of the neighbourhood.

The rules of the street are written anew every day as domestic dramas play out. There is a wonderful scene in which the building’s women shout the news to each other, from window to window, analysing the action unfolding before their eyes, as children scream for it to stop. There is death and heartbreak, allegiances and betrayals, but everything is treated with the same nonchalance, as if a shrug is the best one can muster when money is scarce and life is hard.

There are moments that should be small, because the events are small, but they are made weighty and beautiful: Lenù stepping forward to hand Lila the perfect stone with which to counterattack the boys who are after her; the moment they hold hands at the door of the local bogeyman, Don Achille, who, in this episode, is a faceless spectre made up of stories and rumours. It does a lot with a little.

Lenù and Lila are different from those around them, in their energy and their brightness. They fascinate each other, although not in equal measure; tensions, as banal as they seem in childhood, are beginning to take shape. There is love and rivalry, a desire to embody the other person and to better them at the same time. It is a period piece, but it is timeless, and it is a more honest and vivid portrait of the lives of young girls than I can recall seeing on TV. It is also a particularly emotional and internal story, which makes the success of its translation to screen all the more impressive.