Jobs can suck. (Not this one! Everyone is very nice, and there is free Cherry Coke Zero with movie theater ice on the fifth floor.) If you’re past 25, you’ve probably had one that left you feeling like a three-legged whippet abandoned at the pound. Maybe everything was grand, and then there was a regime change, and the new boss won’t talk to you. Then you get demoted after getting blamed for something that was really Dilbert No. 8’s fault. Your sense of self-worth nosedives, and you must seek out a therapist who is not in your network. You wander the streets looking up “gaslighting” on your phone and wondering if it is you who sucks.

This is pretty much the setup for Apple TV+’s “Slow Horses” which begins its delightfully grim third season on Wednesday. OK, there’s a lot of intrigue and gunfire, but at its core it is the tale of precariously employed worker drones making their way through a broken workplace led by a flatulent boss with hair that hasn’t been washed since Guy Fawkes Day 2011. “Slow Horses” is a twist on their place of employment, Slough House, a diseased walk-up in London where the discard pile of MI5, England’s spy service, work shit jobs under the watchful red eye of Jackson Lamb, a genius, rapidly calcifying spymaster who doesn’t play well with others, lives on kebabs, whiskey and a weekly brushing of the teeth. (His dream death is a heart attack on steep stairs after some “dodgy vindaloo.”) Lamb’s charges are in Slough House because of addictions, royal fuck-ups and misplayed office politics. (Except for computer genius Christopher Chung’s Roddy Ho, who is there for simply being a computer genius dickhead.) MI5 keeps them around for off-the-books work too unseemly for “The Park,” and as easily blamed sacrificial, uh, lambs when things go wrong.

Gary Oldman plays Lamb as a cynic with a diseased heart of something that is not quite gold. Oldman once portrayed John Le Carré’s George Smiley, so imagine spymaster Smiley gone to seed, a seed buried at the bottom of a waste treatment plant. He sharpened his yellow teeth in the last days of the Cold War, and 30 years later he’s been relegated to the third division of the spy game at Slough House where he manages misfits while smoking, drinking and living in his sad office. His nemesis is the perfectly coifed Diana Taverner, played by Kristin Scott-Thomas as an ice queen inexpertly climbing to the top of MI5’s greasy pole. They’re enemies, but enemies that need each other. An actor’s master class occurs when the two occasionally meet to exchange information on a grubby bench on the Thames. Taverner taunts Lamb for his fall from grace, while Lamb responds with vulgar bon mots and a crop dusting of her personal space. “Lady Di,” as her subordinates call her, looks like merely being in Lamb’s presence is draining her of her well-calculated chicness.

The plough horses at Slough House are a delightfully diverse lot in both ethnicity, gender and dysfunction. The lead mule is River Cartwright, played by the habitually great Jack Lowden, the scion of MI5 royalty who got played in a training exercise that resulted in the theoretical deaths of thousands, and avoided the pink slip only because his granddad (Jonathan Pryce) is MI5 royalty. His chief competitor for competence includes Louisa (Rosalind Eleazar), who lost her partner last season, and is now seemingly on a bender of anonymous men and risky behavior that might end her days. This season, Aimee-Ffion Edwards’ Shirley Dander and Kadiff Kirwan’s Marcus Longridge, coke user and gambling addict respectively, play larger roles in the pursuit of, if not justice, mitigating the amount of death and injustice being dropped on unsuspecting pawns. The actors are all perfectly slotted in their surliness, thanks to the magic of legendary casting director Nina Gold, who has now cast “Slow Horses” and “Bad Sisters,” Apple TV+’s two most accomplished shows.

Part of the charm of “Slow Horses” is that Lamb and the Slough House inmates still possess some kind of moral center. Lamb’s moments of humanity are usually tied to coming to the aid of his spies, aka his “Joes” — some alive, many dead. His conscience, as much as it exists, is his assistant Catherine Standish, played with mousy brilliance by Saskia Reeves. Lamb has a soft spot for Catherine — well, because he murdered her previous boss, while Catherine thinks it was a suicide that she could have prevented if she had not been an alcoholic. Now, she spends her days at AA meetings and trying to prevent Lamb from blowing up what remains of his career.

Season 3 revolves around Standish’s kidnapping after an AA meeting, and its ties to a MI5 cover-up that involves keeping their dirty laundry private by offing their own agents. If there’s a fault in the third season, it is that it seems the popularity of “Slow Horses,” particularly in the UK, has upped the production budget. This is most evident in the season’s start with a “Bourne”-like chase scene through Istanbul, and, later, a “Heat”-ish shootout that goes on a bit too long. (I’d much rather have 15 minutes more of Lamb slagging off his underlings in the unfashionable Barbican neighborhood of London.) But those are minor quibbles. The play­­­ — not so much the gunplay­ — remains the thing.

“Slow Horses” suggests that the workplace behind the camera is just as important. In addition to Gold’s contributions, the series is centered on ace material from the tart spy novels of Mick Herron, with scripts either written or overseen by Will Smith, a former producer on “Veep.” You can see that show’s influence in “Slow Horses’” moments of black comedy, but this show has a soul that “Veep” never had. We glimpse actual humanity in some of Lamb’s more benevolent antics; in River dealing with his beloved grandfather slipping into dementia; and in Scott-Thomas’ verbal wars with her boss, the equally steel-willed Ingrid Tearney played by Sophie Okonedo.  Oh yeah, Mick Jagger loved the books so much that he provided the acidic theme song.

I’d end this with a terrible line about how the horses of Slough House may be slow, but the show is a thoroughbred. That is if I hated my job, but I don’t. (Did I mention the free Cherry Coke Zero?)

Just watch.

The first two episodes of “Slow Horses” premiered on Apple TV+ on Nov. 29, and the remaining four will be released weekly on Wednesdays