Agents of S.H.I.E.L.D. may be most thought of as testing the television storytelling waters by being the first ongoing series to be an extension of a (meta) feature film franchise, but the show actually has pushed the envelope in other ways over the past three years. Marvel’s first (and, so far, longest-lived) TV venture has proven to be remarkably fluid in a way that few other series have.

S.H.I.E.L.D. started off with a very specific, mostly curtailed premise: Agent Phil Coulson (Clark Gregg) gets a small, five-man team to help support him on his mission to track down 0-8-4s, those unknown – and usually alien – items or individuals that seem to keep popping up all over the face of the Earth (this is the mission audiences see him engaged in in the movies and the Marvel One-Shot short films, even if they didn’t necessarily know its technical mandate at the time).

This changed, of course, once the final stretch of season 1 arrived and Captain America: The Winter Soldier revealed that Hydra had been hiding inside S.H.I.E.L.D. (just as it did with Nazi Germany previously) for the past 70 years, and then went on to blow S.H.I.E.L.D.’s secrets wide open, tearing the organization down in the process. Since former director Nick Fury (Samuel L. Jackson) wasn’t able to rebuild his beloved agency in Winter Solder, he decided to do so in Agents of S.H.I.E.L.D., tasking Coulson with creating a newer, sleeker S.H.I.E.L.D. that would hide in the shadows (and, therefore, stay out of the movies’ way).

Director Coulson carried out this mandate in seasons 2 and 3, but thanks to events in the wider Marvel Cinematic Universe (and in the show), the current season sees the situation evolve once again. After Coulson slowly worked his way into the good graces of both the American military and (more importantly) President Matthew Ellis (William Sadler), and after the Sokovia Accords are signed during the events of Captain America: Civil War, S.H.I.E.L.D. is once again an officially recognized entity - one that is allowed to grow and become something much closer to its bigger, more convoluted self at the start of the MCU.

This means a demotion for Coulson (thanks to the fact that, well, his second life is still classified) and the institution of a new director (played by Jason O’Mara), who is keen on breaking up the old gang: while Agents Melinda May (Ming-Na Wen), Leo Fitz (Iain De Caestecker), and Jemma Simmons (Elizabeth Henstridge) are all still stationed at the Playground, only Simmons has direct access to the new boss. Agents Coulson and Alphonso MacKenzie (Henry Simmons), meanwhile, are constantly out in the field, while Daisy Johnson (Chloe Bennet) has gone rogue.

It’s an interesting turn of events – Coulson technically has less power than he did four years ago, at the outset of the show – and while it certainly looks set to upend the narrative status quo yet again, it has the added benefit of coming full circle. Coulson is once again scouring the planet for new cases to investigate, and Daisy has gone right back to her pre-S.H.I.E.L.D. days, when she was a vigilante looking to right society’s wrongs (though now, instead of being a hacktivist, she’s a fully powered Inhuman known as Quake). Fitz-Simmons is back behind their science wall, well away from the field, and even May has something of a back-to-basics feel, although it’s less season 1 (when she started off the year as a desk jockey and only “reluctantly” agreed to be Coulson’s pilot) and more season 2 (when she takes on the direct training of Daisy as a S.H.I.E.L.D. agent personally).

What’s even more interesting, however, is the driving force of such shuffling. The role of the Marvel films in Agents of S.H.I.E.L.D.’s production is, of course, a prime motivator here – how could the series possibly ignore such developments as the Hydra reveal or the Sokovia Accords? – forcing it to constantly adapt to a changing narrative landscape that it has absolutely no control over. But there’s also the storytelling modus operandi that showrunners Jed Whedon and Maurissa Tancharoen have very obviously demonstrated during their four-year tenure. It seems that constantly staking out new ground from season to season is just as much a personal predilection as it is, possibly, a corporate mandate.

The first season opened with Agent Phil Coulson’s team tackling a wide variety of seemingly random superpowered cases, though most are quickly revealed to be interconnected, and their overseer is revealed to be one of Hydra’s biggest operatives - serving as viewers’ introduction to the secretive organization’s importance to S.H.I.E.L.D.’s overriding narrative.

Seasons 2 and 3 – the years in which Director Coulson actively hunted the rival agency down – were largely preoccupied with Hydra, even if the conflict sometimes took a temporary backseat to other storylines. All Hydra’s leaders were taken out, whether directly or indirectly at the hands of S.H.I.E.L.D., before the second season came to a close, and even when season 3 introduced two fresh heads of state – one brand new and in the foreground, the other older and very much working behind the scenes – they were similarly disposed of by year’s end. This created the very exciting opportunity for a new and potentially different type of adversary to be introduced in the fourth season – something which just may take a plunge into the mystical, if the new addition of Ghost Rider (Gabriel Luna) is anything to go by.

Hydra also played another key role in the evolution of the series’s overriding narrative: as the grand introducer of S.H.I.E.L.D.’s other dominant throughline to date, the Inhumans. These alien-bred supersoldiers were not only sought by Hydra in order to unlock the secrets to creating its own biologically enhanced weapons, their very existence at the hands of the Kree is ultimately revealed to be the founding principle of Hydra itself. Hive, the very first Inhuman, was designed by the alien warrior race to be the general in their new slave army. When he instead revolted and led a mutiny against the Kree, he was banished to a distant planet, and the humans left behind started what would prove to be a millennia-old secret society to bring him back – thereby merging both of the series’ main plots in one neat twist.

The Inhumans, of course, remain an important element in the current season; after Coulson fought to keep their identities secret, even when recruiting them to be on the short-lived Secret Warriors unit, the Sokovia Accords have won out on the international stage, requiring each of these individuals to once again be registered with the government and to have their activities monitored by S.H.I.E.L.D.. And with Daisy now gone rogue and Robbie Reyes, the human face of Ghost Rider, very possibly having some type of Inhuman connection as well, the panic and alarm caused by their continued presence on the streets could go on to fuel greater conflicts – and, very possibly, the on-again-off-again Inhumans film that Marvel Studios keeps talking about doing sometime next decade.

Yes, having such a revolving door of ongoing storylines is once again partially dictated by the general state of MCU affairs (when Winter Soldier unmasks Hydra, it’s kind of important for the television series devoted to S.H.I.E.L.D. to play out the ramifications), but there’s another, more general mandate at work here, one that is arguably best suited to Marvel’s flagship TV show: every MCU production, no matter its scope or size, is expected to adapt various new elements from the company’s comics lineup (even Agent Carter, the only show to be cancelled thus far). Bringing Quake, Mockingbird (Adrianne Palicki), Deathlok (J. August Richards), the various Inhumans, and now Ghost Rider to life on the small screen more than fulfills this obligation - after all, who knows how long it might have taken for the character to get his own movie within the MCU canon, now that he’s become commonly associated with Nicolas Cage.

Just what new surprises and deviations the fourth season will bring are, of course, entirely unknown at this point, but they’re undoubtedly out there, waiting to make the fifth season every bit as unpredictable – and, therefore, as compelling – as its predecessors.

Agents of S.H.I.E.L.D. continues with “Meet the New Boss” Tuesday, September 27 at 10:00 pm on ABC.