Oh, the paradox of Marvel's "Agents of S.H.I.E.L.D. As the ABC spy drama soldiers through its fourth season, it's more apparent than ever that this show has two sides. For long stretches of time, the action and ideas at the heart of the drama will drag or meander – delivering thoroughly forgettable superhero battles. But just when you thought you should give up on the show (or maybe after some of you did), "Agents" will bounce back with a baller hour of television.

We may never fully solve this paradox to our satisfaction, but at least for this week it doesn't matter. Last night's finale to the "LMD" era of the show was everything you want from a super spy drama. Written and (for the first time) directed by co-creator Jed Whedon, the hour was a taut, tense thriller backed up by strong human performances, an insanely fast pace and more twists than you can shake an android at. It may be the best single episode the series has ever delivered.

Most of that comes from a very simple but very satisfying premise: S.H.I.E.L.D. headquarters has been taken over by a quartet of Life Model Decoys who are bent on leveraging the organizations power to wipe out all Inhumans. But their actual goals are secondary, even forgettable, in the face of the personal story playing out. As things open, Fitz and Simmons are literally surrounded by these android double agents as faux versions of Coulson, Mack, Mace and Daisy flow through the base in a claustrophobic ballet that feels like a robotic version of an Aaron Sorkin "walk and talk" show.

As the science whiz's work to separate themselves from the leadership and launch a counter attack, we see faux-Coulson give the big pitch for "the Framework" – the virtual reality that holds the real agents captive and also birthed the views of the LMDs – to the LMD May that he's holding captive. The big idea is a world without pain. The Framework is a reality that humans should willingly submit to because it will erase their greatest regrets. All they have to give up is their body. But the real tension here is not in the allure of that brave new world but but the breakdown between kinds of LMDs. Coulson and his ilk have always known they're androids and as a result have taken to the Framework's goals like religious followers. But as this May came into the world thinking she was the real deal, she still holds onto vestiges of humanity.

That dynamic is reinforced by the relationship between LMD Aida and her creator Dr. Radcliffe. While the android is struggling to come up with a reason to keep humans alive outside the framework – including the Inhuman-hating Russian who pulled together the resources for Radcliffe's plan. Despite the fact that he's been inspired by the mysterious Book of Darkhold, the good doctor still resists the act of killing the bodies of his captive agents, creating a paradox for Aida who struggles mightily to grasp human emotions like jealousy and anger.

In any other episode of the show, these competing plots would slowly unfurl over the course of an hour – usually building to a final twist in the last minutes to propel the audience on another week – but not this time. As an arc-ending adventure, Whedon's episode ratchets up the reveals and the anguish to a level never before seen on the show. Because Fitz is actually an LMD! And this reveal plays out in a teary, bloody Mexican standoff between the kool-aid drinking Scot and his love Jemma – not only making us wonder what is real but also breaking new grounds for the character. Faux-Fitz admits that the entire LMD fiasco is his fault before revealing that joining the Framework has allowed him to finally open up about his plans to marry Simmons.

And before we can even watch poor Jemma process what this means, she stabs the virtual likeness of her love to death (or really stasis) before we also see that...twist! Daisy's been herself the whole time! Discovering an entire squadron of androids in her likeness meant to ensnare all Inhuman's via subterfuge, the team's resident superhero needs to quake her way out of the crisis. And from her throwdown with Mack amid rows of her half-dressed doubles on to Daisy's no-holds-barred battle with faux-Mace, the fights at the heart of the episode are some of the most bracing and brutal in the show's history. This stuff is one part "Die Hard" and one part "Fight Club" as Whedon's camera work finally show Daisy in unrepentant superhero mode – a level of emotional action storytelling that the show wasn't even able to achieve last year when she battled Ward to a standstill.

What's better, the action moves along at such a clean, clear clip that there's still time in the hour for plenty of heartbreaking character moments. The reunion of Daisy and Simmons moves from another paranoid standoff (what a line is "you can't know until they kill you") to a tight embrace in seconds with the visuals lingering on their real human connection in a cathartic moment that's equal parts relief and panic. Across the world, Aida solves the paradox of her programming by slitting Radcliffe's wrists only to load his mind fully into the Framework – a move that theoretically should make him happy. Even little moments that should pull you out of the story barrel roll into more satisfying conclusions. The escape of Daisy, Jemma and a trio of agents (including the odd-fit Davis who despite being included again has less to do than a nameless female agent who we'd much rather see pulled into the main cast) should irk with its layers of implausibility. But from a red light firefight reminiscent of "Alien" to the quick opening of the Zephyr ship's launchpad that evokes "Star Wars" cinematics, the craft at work here makes the whole sequence a joy to watch.

The hour couldn't end without a number of final twists as faux-May proves the last obstacle and the final ally our heroes need to escape and hunt down the submarine holding the real Coulson and company. And as a bonus, sitting on a raft of explosives explaining to fake Phil how pain and regret are essential parts of humanity, we finally get a moment from the LMD May that feels earned. It's a shame she had to finally find a voice just before blowing all the androids to Hell, but them's the breaks.

Like a true Marvel event, the story couldn't simply end but instead sets up everything for the next major arc in this corner of the universe. Reunited with Yo-Yo and their trio of helpers, Daisy and Jemma must plug themselves into the Framework remotely in order to track down the team. This idea sets up the next level in more ways than one. Not only are strong stakes established for the entire mission (the old "if you die in there, you die out here" chestnut is compounded by the fact that you might just die in there anyway), but we're offered a tease of where everyone would live if they had none of their S.H.I.E.L.D.-driven regrets. Coulson's an average teacher. Mack's a happy father. Fitz is a science whiz with a mystery woman in tow. And Jemma is...dead? Well, maybe not everything is regret free as we find in a final pair of twists that the Framework's virtual world features May still and agent in Hydra's Triskelion! Plus, Daisy wakes up to a supposed happy life with her hubby Grant Ward!

Leaning hard back into the "S.H.I.E.L.D. Vs. Hydra" concept is a brilliant move for the show, even if it is only a dream. Not only has this series always been at its best when it holds onto that superspy baseline, it also fully jettisons the Inhuman saga onto its own impending Marvel show once and for all. With their best villains in the mix, major mysteries to be solved and at least a few turncoats on the main team, "Agents" is in its best creative space since the end of Season 3. Of course, there's a heavy chance that it will squander things the same way it did most of the LMD arc, but until April, let's all live in hope that it'll stay this cool.