"Just what are these things Lewis?" demands Inspector Morse. "Fractals, they're called," Lewis replies. "New geometry, computer generated, to do with chaos – why, if a butterfly flaps its wings in the Amazon jungle, you have a hurricane in the Himalayas." Morse looks on, incredulous. They pull down the fractals poster in teenager Vicky Lewis's bedroom and find the wall behind plastered with rave flyers. Morse puts on her headphones and presses play on the stereo. "There's something in here, play that bit again!" he yells over an earful of acid house. "That's the 'Hallelujah' chorus... conducted by Sir Adrian Boult!"

While Cherubim & Seraphim is the best episode of late 80s-early 90s TV detective drama Inspector Morse, the important truth of the series is that it's not really a detective drama at all. Rather, it's a show about Morse, the most ornery detective who ever lived. Colin Dexter, on whose books the programme was based and who has a cameo in every episode, said that the genesis of Morse was the fact that he wanted to write books about a very clever man who could understand clues when nobody else could. "I gave him a few of my qualities," he said, confusing tastes for personality: "a liking for Wagner, crosswords and real ale." He added that Morse was "a melancholy man" – which is a nice way of saying that he regularly blows up at people at high volume. Morse explodes when a) a coroner expresses annoyance at being called out of hours b) a pub landlord calls time on lunchtime service just as they walk in the pub c) Lewis buys him cans of bitter in lieu of said lunchtime pint(s) ("That's not real beer Lewis!") and in this episode, the moment Lewis suggests Morse's beloved step-niece may have gone to Slough ("Marilyn wouldn't go to Slough!" he scoffs). Cherubim & Seraphim is also one of the few times we get a little insight into Morse's upbringing and feelings, although John Thaw said Morse was the sort of man he would be a little frightened by, because he “lived on such a short fuse”. Could there be a better character to come up against the strangeness of rave culture in a mainstream, prime-time TV programme beloved of Middle England?

Cherubim & Seraphim was first aired 15 Apr 1992, a month before the infamous Castlemorton Common rave, but a few years after moral panic and subsequent police crackdowns had begun to cause problems for the free party scene. It was one of director Danny Boyle’s first big gigs and he later recalled that when he got the job he was embarrassed to tell his dad because the pay was more than he had ever earned. You might even see this episode of Morse as being a Home Counties prequel to Trainspotting, the film with which Boyle would break through a few years later before he went on to direct Olympic opening ceremonies and achieve Hollywood fame with the likes of The Beach and Slumdog Millionaire. The plot focuses on the rural Oxfordshire rave community and three promising teenagers who have died in suspicious circumstances after finding paradise in an industrial unit in Slough. The episode weaves together chaos theory, psychonaut literature, Bloomsbury poetry, the free party scene and pirate radio – the latter a crucial piece of the puzzle.

It opens with a rave in a damp former brickworks: lasers; acid house; big fish-little fish silhouettes on the dancefloor. A crowd sprints out of a warehouse into the grim morning, towards a post-party bonfire. People peel off until just three lone ravers are left, gazing into the flames. They give each other the universal 'uh-oh' look that means: the party's over, everyone's gone home, but we all remain hours away from landing back on planet earth. Their deaths are the beginning of the episode, and the prompt for its red thread: a reckoning with the free party scene's drugs, music, and community, through the lens of a well known crime drama.

While Cherubim & Seraphim begins as a troubling and dark piece of Sunday night telly about teenage deaths, the narrative flips to a rave 101 somewhere between the scene in which party organiser Charlie switches on the reel-to-reel in his crusty’s manor house and starts making bangers, and the scene where a pathologist presents a mystery drug he found in one of the deceased teenager's stomachs, complete with bibliography for interested suburbanites: "It's what the trade describes as a mood enhancer," says the pathologist with a fruity flourish. "Is it ecstasy?" asks Lewis. "E, we call it," he replies, before egging Morse on to give it a go to see what it's like – "Oh go on, Oxford is where Lewis Carroll made Alice eat the mushroom," he chuckles. He continues by rebuking Morse for having the temerity to denounce the young for their use of recreational drugs while he happily destroys swathes of his own brain cells with his enthusiasm for lunchtime pints of bitter. "Are you suggesting this boy..." says Morse "Did an Aldous Huxley?" says the pathologist. "Is that... Brave New World?" says a confused Lewis. "Doors of Perception, Lewis," Morse corrects. "‘Heaven and Hell’, actually," says the pathologist.

However serious the subject matter, often this reckoning is fairly on the nose, woven through the script in borderline comedic scenes best watched on a comedown. Morse fluctuates between grief for the loss of youth in their prime and moral panic about their taking drugs and listening to music he doesn't understand. Exhibit one: A conversation in the office, where Morse says he was frightened of drugs back in the day even though The Rolling Stones once played nearby, and Lewis says he once smoked a doobie in Newcastle but it just made his head spin. Exhibit two: Exposition with a very well-spoken lad in a hoodie running a club in Slough who explains what club drugs are, and Morse is faced with the fact that drug legislation and their relative dangers might not be fully aligned. Exhibit three: Morse and Lewis infiltrate a manor house rave, stumbling around in the back like they're two estate agents at Freerotation. A few shots later they might as well be at the zoo: "What do they drink?" Morse asks, utterly confused. "Water!" says Lewis brightly, who's found a baseball cap and is bobbing his head to the music. Exhibit four: After abducting poor Vicky Wilson from her podium in front of the big CGI baby visuals about a half hour after they watched her drop, they ask her: "What is it like, what does it feel like?!" "You love everyone in the world," says poor Vicky, who is doing fairly well given she's being interrogated by two coppers while absolutely flying.

The Inspector Morse theme tune is by a composer called Barrington Pheloung, who inserted the morse code for Morse in the pattern played by the strings, under a pastoral motif. Sometimes in the incidental music he'd also encode the name of the killer, a cryptic version of the killer's name, or someone else's as a red herring, "just because I'm a ratbag," as he once said in an interview. He also made all the club music in Cherubim & Seraphim. Trying to get a handle on this new music is one of the running threads of the episode: they put some on in Morse's Jag on the way to the party: "It's eclectic this music, that’s the basis of it…” he says, “it's a collage… magpie music – a bit here a bit there – all mixed together". Lewis’ daughter Lynne is also into rave tunes, and Lewis almost closes the colossal generation gap when he knocks on her door and asks where she gets her tapes from, but can’t make the leap to ask her to share some. Pheloung's made-up acid house is pretty decent, and in an even more surprising turn for a 1990s ITV crime drama (perhaps because of the oversight of Danny Boyle) the club scenes are actually good.

This is perhaps a surprise, as neither the big nor small screen has ever been very good at club scenes. The best ones are usually not supposed to be club scenes at all (as in 1985 Polish sci fi O-Bi, O-Ba). Good club scenes are where the camera is a roving eye, a protagonist looking for a friend, lover or dealer. A bad club scene is where the camera is a camera and people dance around it as if auditioning for a club scene: individual entities rubbing performatively on one another as if they're both moving to a different track. Bad club scenes (and in fact, bad clubs in general) forget that hedonism has something in it that demands to be watched and yet is a solipsistic quest to satisfy the ego. In good club scenes, you might say everyone's dancing like nobody's watching, which is the sort of slogan a club would have if Morse were set now, but which nobody had heard in 1990s Oxford.

Morse drinks too much, listens to opera at full blast, and blazes round country pubs in a vintage Jag fast enough to make women dump him (see Masonic Mysteries, another Danny Boyle-directed episode), but because of this, he has a much better grip on the hedonistic lifestyle presented in Cherubim & Seraphim than Lewis – the Robin to his Batman, the Sancho Panza to his Don Quixote – for whom hedonism is nothing but the answer to one of Morse's crossword puzzles, even though he enjoys the huge tunes. Despite that single doobie, Lewis doesn't understand a comedown at all because his wife wakes him up with a milky tea and a freshly ironed shirt every morning, whereas Morse most definitely does. There is an ocean of Big Problem in Morse, as there is in all of us the morning after, even if Morse's route there was Maria Callas turned up to 11 and a bottle of single malt, rather than Jeff Mills and a couple of pingers.

Morse lost in the ocean of Big Problem

When you're going out a lot, the Venn diagrams of friends overlapping in the smoking area and by the front left speaker don't just connect on ecstatic dancefloor moments, they're made in the comedown too; in programmes watched together on sofas with happy brown cups of tea and bacon on soft white bread, or posted to group chats and received in a constellation of beds humming with club grime and fusty pillows caked in make-up. In these moments what you watch is what connects you. It can't be too good, because you're wrangling with your own misbehaviour in the eyes of wider society. It has to suspend the carnival of illusions we call the real world; have wit and power, and quotable bits you can shout in one another's faces at some point in the future. For my lot, it's Pumping Iron; Withnail & I; Do The Right Thing; Nuts In May; almost anything with Nic Cage, Clueless if you're feeling extra soft, and Wall Street, which I request because I want to escape into something where 'climate collapse' only exists as a vague notion that you ought to sponsor a dolphin. What you want is something on the screen that distracts you from the yawning chasm hovering in your blind spot threatening to consume you completely.

Morse was never intended to be consumed as a means of staving off the void as Sunday grinds inexorably towards the return of the working week, which is perhaps why Cherubim & Seraphim is so effective. When it was broadcast, Morse was Quality Telly: a show for the boomers who'd grown up with the rough and ready rogue coppers of The Sweeney but had come good and calmed down. They’d swapped the donkey jackets and slugs of room temperature whisky hidden in office filing cabinets for BHS V-necks and sauvignon blanc and settled down in the suburbs to grow tomatoes and watch TV. While The Sweeney's Reagan is not Morse, John Thaw's route from the mean streets of Peckham to the colleges and lanes of Oxford traces the social mobility of large swathes of the Boomer generation who made up the programme’s audience.

There are moments of pastoral calm throughout most episodes of Morse: villages on Sunday, pubs that close after lunchtime, big houses that seem to be affordable. There’s a lot of soft beige food, all of it from Britain, and a general ignorance of the world beyond the polite parts of the city. The sound of sunny suburban idylls clatters throughout: bicycle bells and birdsong. It's a fake idyll, though, and one that's overwhelmingly middle class, overwhelmingly white. It is, as one commenter said: "cleverly packaged British nostalgia". The show's writer Julian Mitchell said it was all about class – the hierarchy of the police mirroring the ingrained divisions of wider British society. But in Cherubim & Seraphim there is, momentarily, a question raised about what the stasis of suburbia offers future generations: "Starter homes! God almighty," Morse laments. "What sort of life do we offer our young people, Lewis? School, then college, then marriage, a starter home, then children, a two bedroom semi..."

Choose a job. Choose a career. Choose a family...

"If you do well you just about get to four bedrooms when your kids leave to buy starter homes of their own…” he continues. “This British home owning democracy is really a form of slavery."

Choose your future. Choose life. Choose episode five, season six of Inspector Morse, which is not a guilty pleasure, because the morning after a big night out there are no guilty pleasures – there is only guilt.