In Lisa McGee’s show “Derry Girls,” about a group of teen-agers growing up in Northern Ireland during the Troubles, the threat of violence—in the form of car bombings and street riots—was portrayed as so commonplace that it became, effectively, a nuisance. It wasn’t just terrifying; it was annoying, getting in the way of salon appointments and nights out. In the pilot episode, the friends are on their way to school when armed British soldiers board the bus they’re on at a vehicle checkpoint. Waiting for them to finish, one girl yawns, while another ogles the uniformed men. “Do you think if I told them I had an incendiary device down my knickers, he’d have a look?” she says. “Some of them are rides!”

Much of the comedy of “Derry Girls,” which became a surprise smash hit on Netflix, derived from this juxtaposition: the mundane—a school ride—and the unthinkable. The main character, Erin, and her friends are animated by schemes that have nothing to do with the turbulent times in which they happen to live. They want to meet boys. They want to ditch class. They want to wear jean jackets instead of school blazers and learn how to smoke. It is part of the charm of the show that the habits and wayward desires of teen-age girls—their in-jokes and obsessions, the everyday indignities of adolescence—are foregrounded rather than trivialized, even against the backdrop of serious sectarian violence. Girls just want to be girls, without having to worry about explosions.

If violence was ambient background noise in “Derry Girls,” it has come front and center, albeit in a more cartoonish fashion, in McGee’s new show, “How to Get to Heaven from Belfast.” The eight-episode comedic murder mystery, which premièred on Netflix last month, and quickly gained a following in the U.K., shares some similarities with McGee’s previous project. Once again, we are mostly in Northern Ireland with a tight-knit gang of girlfriends who wind one another up and hatch plans in rapid-fire dialogue. This time, however, we are in present-day Belfast, and the girls are grownups: thirtysomething women who were closest when they attended Catholic school together, twenty years earlier. Back then, they were inseparable and—maybe, possibly—did something one dark night in the woods that none of them has been able to forget.

Since that evening, their lives have gone in vastly different directions. There’s Saoirse, played by Roisin Gallagher, a successful television writer for a popular crime show called “Murder Code” who’s on the verge of burnout. (“I wanted to write plays. What happened?” she says acidly, after an awkward lunch with the show’s bratty star, Marnie. “You realized you’d need to buy stuff,” one of her colleagues replies.) Robyn, played by Sinéad Keenan, is a wealthy, stressed-out mother of three boys, who says things like “You can be in bits and have your highlights done. The two things aren’t mutually exclusive.” Dara, played by the delightfully expressive Caoilfhionn Dunne, has given up most things to care for her aging mother. The three women reunite to attend the wake of their estranged school friend, Greta, played by Natasha O’Keeffe, once the fourth in their gang. When they arrive at Greta’s home, however, the vibe is off, and not just because the friends are hungover. Saoirse decides to open the casket to slip a photo inside and—wouldn’t you know it—the body’s not Greta’s.

This revelation provides the perfect excuse for the women to leave their various real-life problems behind in order to play amateur detectives as they try to uncover what happened to Greta (and, indeed, the identity of the very dead woman inside the casket). Their first discovery is that they make for terrible sleuths. They are skittish, easily spooked, often sniping at one another, as old friends do. (“What in under Christ is she wearing?” Robyn asks, as Saoirse arrives in a wide-legged trouser suit. “Are they pajamas?”) Saoirse, who is engaged to one of her “Murder Code” colleagues back in London, has the hots for a twenty-six-year-old member of the Irish Garda who has come to assist them. Dara has a bad habit of filling Robyn’s diesel car with petrol, and the trio often find themselves breaking down outside remote Irish towns, with storm clouds on the horizon. “What if we die out here?” Robyn asks Saoirse, as they wait for rescue. “When they discover the bodies, they’re gonna have to record that you’re wearing pajamas. And that’s fucking mortifying.”

Like Saoirse, McGee began her career writing plays. She won a prestigious attachment to the National Theatre in London just after completing her university studies in Belfast. An earlier show of McGee’s, “London Irish,” followed a group of Northern Irish friends in their twenties drinking their way through London. They were British, but also unshakably Irish—they were somehow made more Irish by living in London—and she has given Saoirse a similarly complex relationship with her country of origin. When Saoirse insists that she lives in London, Robyn counters, with the assurance of a very old friend, “You don’t live in London!” “You work in Belfast,” she continues. “Your TV film is made in Belfast. You’re in Belfast about eight months of the year. Why can’t you admit you live in Belfast?” Saoirse can only respond, huffily, “Because then I’d be somebody who lives in Belfast—not that there’s anything wrong with that!”

The show itself makes no qualms about being Irish. It seems to revel in the rolling landscape and horrendous weather and small-town charm of the place. The Irish comedian Ardal O’Hanlon, best-known from the beloved Irish sitcom “Father Ted,” makes a cameo as an innkeeper in the tiny village of Knockdara. Giving the women directions to Greta’s house, he offers them convoluted advice to take “a left, a right,” and “a left that sort of feels like a right” until they arrive at a field where they should “look for a scarecrow with one arm dressed a bit like . . .” “Could you maybe just call us a cab?” Robyn interrupts. One key scene takes place on the set of the popular “Late Late Show,” a real-life Irish late-night show that was first broadcast in the country in 1962. The program’s host, Patrick Kielty, plays himself. These elements can sometimes feel superfluous, as when the women crash into a boisterous pub on St. Patrick’s Day, but they also serve to remind the women of their past over and over again. You’re all tangled up in your history, they seem to say. You won’t be able to outrun it.

Though “How to Get to Heaven from Belfast” is ostensibly a murder mystery, it often feels more like a buddy comedy. I enjoyed the twists of Greta’s story—especially the deadpan ferociousness of Bronagh Gallagher, who plays a mysterious and violent woman inexplicably tailing the group—but I could have done without some of the more bizarre turns in the later episodes. (Without giving anything away, I would not have missed an entire plotline involving a corrupt society concealed behind a beauty salon.) I kept coming back to the show instead for its bleakly funny portrait of middle-aged friendship. “We’re dying now? That’s it, is it? That’s the latest?” Robyn says, outraged, when she hears the news about Greta. “We should not be dying. We’re thirty-four years of age, for Chrissake.” “We’re thirty-eight,” Dara corrects her. These are women who know one another too well. They have heard every anecdote, every gripe, hundreds of times. It’s an intimacy that is both infuriating and joyful, and deeply satisfying to watch.

It can be hard to let old friends change. Part of you will always see them as the kid they once were, without the baggage one acquires simply by living. It’s a seductive thought—moving through life unchanged—and the show toys with it in both silly and serious ways. In one episode, Marnie, who plays a homicide detective on “Murder Code,” comes to Saoirse with an idea. “What if, this season, there’s no murder?” she says, breathlessly. “No murder?” Saoirse replies. The character is a homicide detective. “That’s not all she is,” Marnie says. “It’s the main bit!” Saoirse says, tightly. Later, Greta’s mother articulates an ideal she once held: “I mean, can you imagine? If we could separate ourselves from our trauma, completely, totally. Not learn how to manage it, not numb it, but to leave it behind.” But you can’t erase someone’s past, just like you can’t take the murder out of “Murder Code.” It’s the main bit.

Early on in the series, when Saoirse, Robyn, and Dara find themselves stranded in Knockdara, they book a room at a hotel hosting a nostalgic, early-two-thousands-themed party. The women watch as teen-agers dressed for the occasion fill the hotel’s bar. “Pump It,” by the Black Eyed Peas, comes on. (The show is peppered with the kinds of songs the trio would have blasted in their bedrooms growing up. “C’est la Vie,” by B*Witched; “Hot in Herre,” by Nelly.) “I had that top! Robyn says, incredulously, as she looks at the party-goers. “And that bandanna!” They decide to get very drunk. They are on the dance floor pulling out their signature moves when the music suddenly turns melancholy. The lights grow hazy, and the friends seem to see the ghostly images of their younger selves dancing alongside them. It’s an eerie scene, pierced by longing and the kind of alienation that can happen in a crowded room. The older women slow to watch their past selves. They are wearing their school uniforms and show no signs of stopping. ♦