“My Brilliant Friend,” HBO’s first original series from Italy, is back for Season 3 after a two-year hiatus.

That’s good news, and it was worth the wait, but it arrives with a caveat: there are many moving parts here, both via characters and story arcs. So, if you’re not caught up, it’s advisable to read a summary of Season 2 before plunging back into the ongoing saga of childhood friends Lenu (Margherita Mazzucco) and Lila (Gaia Girace), the protagonists of Elena Ferrante’s novels upon which the series is based.

The eight-episode third season, premiering Monday, Feb. 28, is subtitled “Those Who Leave and Those Who Stay.” It fast-forwards to the 1970s and finds Lenu and Lila, who have grown apart and have no contact with each other, in polar-opposite circumstances.

Lenu is now a moderately successful author who is perturbed that her novel is considered racy and is criticized as such — which is not what she intended. She’s engaged to Pietro Airota (Matteo Cecchi), a young university professor from a wealthy and respected family. Lenu is not thrilled about her upcoming wedding and secretly pines for her old boyfriend, Nino (Francesco Serpico). And despite (or in spite of) her success, issues persist with her envious/ jealous mother, Immacolata (Annarita Vitolo). It’s an already-tense scenario that’s aggravated when Lenu moves back in with her parents and siblings in Naples.

Lila, who enters the narrative in Episode 2, is working a dead-end, soul-crushing job in a filthy sausage factory where she’s sexually harassed by her boss, Bruno (Francesco Russo). Her feisty, unconventional spirit is now extinguished; she’s persona non grata to her family back in Naples and is estranged from her husband, Stefano (Giovanni Amura), who’s moved on. Lila lives in a modest apartment with her young son, Gennaro, and with her good-hearted (platonic) friend Enzo (Giovanni Buselli). She’s teetering on the verge of a physical and nervous breakdown — and, when she does collapse, she turns to the only person who will understand: Lenu.

As mentioned earlier, “My Brilliant Friend” is a sprawling narrative (with English subtitles) and multiple layers needled into the fabric of both both Lenu and Lila’s world. It’s tough to keep track of all the supporting characters, many of whom return from the first two seasons.

The new showrunner/director, Daniele Luchetti, does a commendable job of integrating the country’s ’70s-era current events into the episodes and, in turn, tying them to the protagonists. There’s a pulsing undercurrent of Italy’s political tensions — clashes between communists, socialists and fascists — set against the backdrop of student protests that not only open Lenu’s eyes but reach the doors of the sausage factory with violence and calls to unionize … as Lila renounces its deplorable working conditions and its management.

Season 3 was shot on location, so there’s no shortage of picturesque (and not so pretty) scenes in Naples and Florence. According to Variety, there was speculation in the Italian press that Mazzucco and Girace, both 18, were too young to play older versions of Lenu and Lila. Luchetti, however insisted they return for the sake of continuity and because he felt they could handle the emotional weight of their maturing characters.

He was right on both counts.