MI5 operative Milner is telling conspiracy theorist-turned double agent Wilson about the requirements of his new job. Wilson sighs. "Am I capable?" he asks, despairingly. Exchanges like this are inevitable when the paranoid but creative vigour of the '70s meets the impotent languor of the current decade; a decade so indistinct and underpowered that it doesn't even have its own nominal abbreviation. And the thing is, Wilson's doubts are entirely well-founded. He probably won't be capable of anything much beyond acting as a bewildered patsy. But that's okay. Because nothing much beyond that will be expected of him. Both Milner and Wilson himself know that he's at the mercy of forces way beyond his control.

In early 2013, the first season of writer Dennis Kelly's conspiracy thriller Utopia made a splash on C4 thanks to its expertly calibrated mixture of tangled plotting, jarringly atmospheric direction and stylised ultra-violence. The first episode of this second run takes us right back to the beginning. What were the roots of the Janus population control conspiracy? How did the protein containing the Janus DNA end up in the bloodstream of tormented Tank Girl Jessica Hyde? And how did Milner become so jaw-droppingly cold-blooded?

This season two opener is a bravura exercise in the detournement of real-world history in order to milk its story-telling, myth-making potential. Utopia reimagines the present and future by reinventing the past. As such it's both an astute critique of conspiracy theories and a willing participant in their possible creation. Were the assassination of Airey Neave, the 1979 vote of no-confidence in the Labour government and the Three Mile Island nuclear disaster linked? Of course not. But even so, Kelly plays audaciously fast and loose with dates, means and motives in order to construct his disturbing, mischievous thesis. And, as he juggles with the lingua franca and events of the '70s, his series has plenty to tell us about today's TV landscape too.

Is there a common thread running through current British TV? Consider the '70s, where we join Milner, Jessica et al as they stumble around in the power blackouts and wallow in the filth of the winter of discontent. Think of a contemporaneous show which is now established as a key component of the British TV canon. Porridge maybe, or The Good Life or The Fall And Rise Of Reginald Perrin. What oddly subversive pieces of mainstream, prime-time entertainment they now seem. A querulous and dissenting career criminal with whom we're supposed to identify and sympathise? A pair of suburbanites who reject conformity and materialism and mock their aspirational and conservative neighbours mercilessly? A man driven to suicidal despair by the world of work and the intangible nausea generated by a settled but bloodless family life? And all of these played for laughs? The 70s were weird. Looking back, the asylum really does appear to have been left in the hands of the lunatics.

But what of the '80s? Consider the unashamedly polemical fury of Boys From The Blackstuff. Or the visionary strangeness of The Singing Detective. Even ITV's hardscrabble recession fable Auf Wiedersehen Pet looks surprisingly pointed and gritty in retrospect. These were shows with real energy and vitality; with ideas that unnerved and polarised and characters who clearly articulated their creators' visions. By the '90s, the Soviet Union had collapsed and it was decreed in some quarters that history had ended. Accordingly, the decade's keynote TV began to gaze inwards towards family, friends and workplaces - think Cold Feet and This Life. The best of it, exemplified by the work of Chris Morris, self-reflexively critiqued the medium itself. The post millennium TV 'golden age', meanwhile, saw British drama dwarfed by US imports like The Wire and The Sopranos which offered universality by probing the dark heart of unchallenged, unrestrained capitalism.

Drawing a line between Porridge and The Wire might seem like a tenuous exercise. But what all of these shows had in common was characters with clear, firm, fearlessly expressed points of view. And that's remarkably rare in today's TV landscape. For now at least, the idea of television as comfort blanket has won. In fictional terms, its victory manifests itself in everything from the 'dark' but predictable, tabloid agenda-driven horror-schlock of Broadchurch to the simultaneously earthy and fantastical communal warmth of shows like Stella and The Cafe. And it's in this context that Utopia is so interesting - because it feels like a genuine attempt at truth-telling and a very honest recognition of powerlessness.

What Utopia seems to be suggesting is that there are no more heroes anymore - or if there are, they're rendered impotent by the scope of their mission. It might seem like a paradox in the light of our current societal fetishisation of the notion of choice but recent British TV heroes (or indeed anti-heroes) with real agency are comparatively rare. Instead, things happen to them. And so it is in Utopia. None of the characters here are taking back power or even, like Reggie Perrin or Norman Stanley Fletcher, vainly but heroically challenging it. Instead, they're cowering in the face of it; they've found themselves - pretty much by accident and misfortune - in the middle of a vast, incomprehensible, impossibly wide-reaching conspiracy that they can't hope to understand. It's telling that Ian's reason for re-engaging with the Janus project in season two is simply that he wants his girl back. Why would he go anywhere near it otherwise?

So, if powerlessness is the key to much of this decade's TV, how did we get here? We hear so much about the crisis of disengagement - how politics and civic life has never seemed more poisonous or more irrelevant to those who have to live with the decisions made on their behalf. We've all come to the conclusion that power is not maintained by politicians - and Utopia's central plot is fuel for those who point to lobbyists, hidden hands and corporate interests as the unaccountable wielders of real power. Government ministers in Utopia are ideologically neutral. They're also cynical and more to the point, helpless - doomed to drift listlessly without the steering of drug companies and omnipotent secret service operatives.

But eventually, even this feels like a smokescreen. And this is the source of both the true horror and the true brilliance of Utopia. Most dramas play with fairly well-worn signifiers of 'darkness' - paedophile rings, people trafficking, state secrets, espionage and corruption. But usually, it's possible to dismiss these as either ugly singularities or wild speculations. But at the heart of Utopia is the crisis of over-population. And ultimately, over-population is the elephant lumbering around in the real world's living room. The realpolitik facts surrounding it are impossible to ignore and this knowledge adds both a layer of possible plausibility and a grim moral dimension to Utopia - faced with these fast-encroaching realities, who can really say which potential solutions are defensible and which are grotesquely fascistic? The viewers of 1982 knew what they were supposed to be thinking about Boys From The Blackstuff. But which side are we supposed to be on here? The dilemmas bedevilling the characters are reflected right back at the viewer. Now that really is powerlessness.

Dennis Kelly is, of course, well aware of this. Indeed he's stated that he chose this issue to animate the black heart of Utopia precisely because it's the problem that defies the good intentions of the most rational, liberal and progressive among us. For all the fond humour at the expense of conspiracy theorists and graphic novel nuts, the drama can't help but point out that a crisis is being wilfully ignored by the rest of us because it's simply too vast and terrifying to be truly reckoned with.

And it's here that Utopia stops being simply a drama and becomes a satire too. Firstly, there's the show's immaculate branding - somewhere between a drugs company and a mid-market fashion label and something that no pre-millennial TV drama would have felt remotely necessary. But what is a brand if not someone else's imposed and idealised version of reality? And so - Utopia seems to be saying - how do you like this reality? Then there's the horrific, stylised violence - most often perpetrated by Arby and Lee who come across as the terrifyingly yet amusingly blank result of a focus group study of the banality of evil. It's simultaneously guiltily titillating and utterly chilling. Because for all of the violence's artful invention, in this just-about plausible version of reality, this is how things get done. Most pointedly of all, the climax and trigger of this series looks set to be 'V-Day' - a delicious parody of one of those pointlessly feel-good Sport Relief-style communal backslaps - this time involving the supply of medicine to the developing world. And underpinning all of this, there's the distinct absence of any solution that wouldn't cause utter outrage if suggested in public and therefore, a big problem that isn't going anywhere.

So, with its unique and heady mixture of black humour and existential impotence could Utopia be the emblematic TV drama of the decade? Quite possibly. We live in the age of algorithm-driven consumerism, of capitalist realism, of state surveillance that's no longer hidden but seems almost entirely accepted anyway. We live in a world which has just reacted to an unprecedented crisis of capitalism by destroying essential public services in order to restore almost exactly the same system that caused the collapse. We live at a time when our knowledge of the extent to which our institutions are dysfunctional and corrupt is matched only by our disinclination to challenge them. And, as this series seems to be saying, the scariest thing is, that's by no means the worst of it. Utopia indeed.