It's quite a cheeky touch to open your four-part political thriller with the question "Seen enough?" Who, after all, could answer "Yes" that early in the day, particularly as Secret State, Robert Jones's very free adaptation of Chris Mullin's thriller A Very British Coup, opens with a tantalising vision of local apocalypse. A pair of very shiny shoes is crunching through the cinders of a disaster zone – revealed, when the camera pulls back, as a blasted Northern town.

The shoes belong to Tom Dawkins, the Deputy Prime Minister, who is inspecting the aftermath of a refinery explosion; the question is posed by his political aide; and the answer turns out to be "Not quite yet". Crouching to pick up a child's mitten, Dawkins discovers to his horror that it still has the child's fingers inside it. I suppose the squeamish might have decided to cut out at that moment, but most people watching will surely have resolved to stick around for more.

The destroyed refinery belongs to a petrochemical company called Petrofex and, wouldn't you know it, the Prime Minister just happens to be at their headquarters in America for a conference. On the way back (in an executive jet lent to him by the company), he consults with his DP on the political fallout of this accident and then foolishly says this as they hit a bit of turbulence: "It's a little rough up here. We're almost through it now." Oh no they're not. The plane disappears and overnight melancholy, sorrowful Tom Dawkins – played by Gabriel Byrne as one of those men who bears the woes of the world on his shoulders and doesn't bother concealing the fact – finds that he's in charge.

He's got plenty to fret about. A freelance journalist is hinting that Petrofex has been negligent (and since she's played by Gina McKee, we naturally assume that she's telling the truth). His intelligence chief thinks it might have been terrorism rather than weather that brought the plane down. And at the same time, two of his colleagues are jockeying to replace him in time to fight the coming election, which all the polls indicate the incumbent government will lose. And it's at this point that you may begin to ask yourself unhelpful questions. What canny, careerist politician would opt to do such a thing? More to the point, what kind of ministers do their plotting in open view of their rivals? At such moments, Secret State doesn't just fail to fit our knowledge of politics, it doesn't fit our knowledge of humans.

Worse is to come. The media have a presence here as set-dressing, but not as the pressing (and minutely managed) anxiety they would actually constitute in the real world. There's a telling implausibility when McKee's character doorsteps Dawkins at the memorial service for the PM: she's standing squarely in front of a phalanx of press photographers, but instead of hospitalising her for blocking their shots, they just meekly let her get on with it.

The conspiracy seems a hand-me-down affair, too – with corporate villainy and US-sponsored breaches of civil-liberties (they appear to be able to order up phone-taps like a pizza). And the surveillance state has been granted the kind of perfectly functioning technology that is a fixture in the common forms of paranoia but comparatively rare in truth. I'm guessing it will find a happy audience among those who like to have their prejudices reinforced and aren't too fussy about the realism with which it's done. Me, I'm wondering whether I've seen enough.

Comic Strip Presents... Five Go to Rehab is only explainable by some kind of conspiracy theory, since it lacked any kind of coherent plot or much in the way of jokes. It did have a very impressive cast – all of the originals having succumbed to somebody's arm-twisting to turn up for the 30th anniversary reunion. What a pity the laughs had a previous engagement.

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