‘Slow Horses’ season 4 is my favorite premiere of the year — this is why it’s 100% on Rotten Tomatoes

One of the best shows on television is back — and when I say "one of the best," I mean in the top five. Maybe top three.

"Slow Horses" has been a bit of a dark horse for the past three seasons. The Briitsh spy thriller streams on Apple TV Plus, the lesser-known streaming service that does very little to promote its excellent original content. But the show has always received a ton of critical acclaim/gushing, but it's been slow (get it?) to gaining traction in buzz and awards outside of the U.K. That's changing, though. "Slow Horses" nabbed nine Emmy nominations for its most recent season, including Outstanding Drama Series and Lead Actor and Supporting Actor for Gary Oldman and Jack Lowden, respectively.

Now, "Slow Horses" season 4 , based on author Mick Herron's fourth book "Spook Street," has premiered with its first episode and let me tell you, it's a banger. Literally, since a bomb goes off in the first few minutes. The rest of the 42-minute episode follows the formula of the three previous premieres — and that's a very, very good thing.

Warning:  Spoilers ahead!

'Slow Horses' formula is far from boring

Every season of "Slow Horses" begins the same way: a crisis erupts that MI5 needs to handle and it ties to one of the agents assigned to Slough House.

Slough House is a purgatory for disgraced MI5 agents, who are known by the pun-tastic moniker "slow horses." Their boss, Jackson Lamb (Oldman), is slovenly, flatulent and extremely grouchy — but also brilliant at spycraft.

Season 1 premiered with the kidnapping of a student by a far-right group. Season 2 kicked off with the suspicious death of a former field agent. Season 3 began with the kidnapping of Slough House admin Catherine Standish (Saskia Reeves). Of course, that's boiling the plot down to a very short, simple sentence; there are always side plots that end up connecting to the main story to create an intricate web.

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In season 4 episode 1, a suicide bombing at a shopping mall rings alarm bells at the country's security services. That's not all, though. River Cartwright (Lowden) is seemingly shot in the face and killed by his dementia-addled grandfather, MI5 legend David Cartwright (Jonathan Pryce), who believes someone is following him.

Anyone familiar with "Slow Horses" or really any kind of spy story can easily spot River's death as a fake-out. I didn't think for a moment that the show had gotten rid of its co-lead, and was not surprised at all when River turns up alive and well ... and on his way to France to learn more about the man who was following his grandfather and ended up shot in the face.

Somehow, the suicide bombing and the shadowy forces targeting David Cartwright will tie together. The pleasure of watching "Slow Horses" is seeing all the pieces come together to reveal how and why.

While the show employs a formula, it's a fantastic formula . It never feels tired or "been there, done that." Showrunner Will Smith and the writers make tweaks every season, particularly by bringing in new characters. This is already one of the best casts in the biz, and it just keeps getting better.

I didn't think the 'Slow Horses' cast could get better — I was wrong

"Slow Horses" wouldn't work without its Oscar-winning, Emmy-nominated lead, Oldman. The rest of the main cast is also strong, including Lowden as the well-meaning but often dumb River Cartwright, Reeves as the skittish Standish, Rosalind Eleazar as capable but emotionally messy Louisa, Christopher Chung as obnoxious tech whiz Ho, and Kristin Scott Thomas as Diana Taverner, the prickly deputy director general of MI5 aka "Second Desk."

Every season, the show's revolving sends out some familiar faces and brings in new ones. Last season farewelled Freddie Fox as James "Spider" Webb (dead) and Chris Reilly as MI5 internal affairs muscle Nick Duffy (in a coma).

As much as they will be missed (especially the oily pest Spider), season 4 introduces new antagonists to interest us. The big name is Hugo Weaving, who's playing a former CIA operative turned mercenary named Frank Harkness. He's not seen in the first episode, but will become a factor later on.

Another welcome addition is James Callis as Claude Whelan, the new director general of MI5 aka "First Desk." Callis was terrific as the egotistical Doctor Gaius Baltar in "Battlestar Galactica" (one of the best sci-fi shows of all time), which makes him perfect to play a First Desk who's clearly less qualified than Taverner and has managed to fail upward like so many men do in big organizations. Whelan just might be the character to fill Spider's self-important-yet-stupid shoes.

'Slow Horses' is anything but slow

"Slow Horses" belies its title; "Fast Horses" would be more apt, considering the show's quick pace and short seasons. In fact, colleague Martin Shore binged all of "Slow Horses" in just one week .

Of course, that wasn't a difficult feat. The show has three seasons, six episodes each, so only 18 episodes total. And each episode runs less than an hour long (the average is around 45 to 50 minutes). As I mentioned up top, the season 4 premiere clocks in around 42 minutes.

The writing, while intricate and packed with all the usual twists and red herrings, is trim and taut — all meat, no fat. Every bit of exposition and dialogue serves the plot and the characters. Even seemingly purposeless banter between Shirley Dander (Aimee-Ffion Edwards) and Marcus Longridge (Kadiff Kirwan) adds depth and color. Their bickering in season 3 about which one of them was getting fired proved satisfying when both stepped up to the plate in the finale.

You're never in danger of getting slogged down while watching this series; you'll never feel mired in a subplot that feels aimless and endless (yes, we're talking about you, "House of the Dragon").

In fact, the worst thing about Slow Horses is the weekly release by Apple TV Plus. I could easily binge every season in two weeknights or one weekend day. In fact, I have access to all of the season 4 episodes and forced myself not to view them all so that I could talk about it week to week with my friends without accidentally spoiling them.

Then again, unlike Jackson Lamb with a bottle of scotch, I will enjoy savoring "Slow Horses" a little at a time.

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