Dream sequences usually make me want to pinch those responsible in order to wake them up again - because nine times out of 10 they provide directors or writers with an excuse to abandon the struggle for coherence. But initial misgivings about The Serpent - the first of a series of polemical "Films of Fire" on Channel 4 - turned out to be misplaced. For one thing, this was an unusually literary kind of reverie - a contribution to a long English tradition of polemical visions. For another, it was far more subtle and allusive in its treatment of that liberal monster Rupert Murdoch than one might have suspected.

Marc Karlin's unusual film (how refreshing it is, in the dog days of August, to see something on screen that isn't instantly accessible) took the form of a middle-class derangement. Michael Deakin, architect and one of life's capitulators ("Livingstone admirer by night, Blair supporter by day"), falls asleep on his home-bound train and finds himself engaged in battle with the leviathan Murdoch, a massive figure bound with cords like Gulliver in Lilliput. What followed was a kind of illuminated tract - one which deplored Murdoch's coarsening of national life, but which had equally harsh words for those who had let him do it. An angelic voice (Fiona Shaw) filled the conventional part of the dreamer's guide, and sermonised both about the industrialisation of sex and the impotence of offended intellectuals. Offering to show Deakin his "ancestors", she conjured a tableau of a 19th-century anarchist, sketching plans for a bomb outrage that would never take place.

All this was conveyed with considerable visual invention - whether it was the picture puzzles that described the Voice of Reason (a picture of silver cutlery floating in the air completed the line "her voice was like...") or the overlapping of archive, Dore engravings and film which eventually brought Paradise Lost into the game. Just after you had seen Murdoch deliver his wily McTaggart lecture about the importance of choice and freedom, the film cut to Deakin (played with a nice morose bite by Nicholas Farrell) doodling Eve and the Serpent on his frosted carriage window - the world's earliest example of the case for deregulation. Then Kelvin MacKenzie's face filled out the snake's doodled head as you heard Milton's lines about the "fittest imp of fraud". Blake's remark that Milton was "of the devil's party without knowing it" was relevant here, because Karlin's film acknowledged that Murdoch had brilliantly exploited the values of freedom and democracy which his detractors wish to protect.

The Serpent wasn't perfect - the fact that Deakin's nephew narrated the story seemed to add a pointless layer to the mille-feuille of explication and voice-over, and there were moments when the arguments became a little blurry. But the thoughtful ingenuity of the thing more than made up for that, not to mention the way it salted the solemnity with little dashes of comedy.

I'm not usually in a forgiving mood when it comes to UFO enthusiasts but, watching the opening of Flightpaths to the Gods (BBC2), you have to concede that the markings on the Nazca plains offer an understandably seductive mystery - particularly when associated with the eerily elongated skulls found in burial sites and the drawings of humanoid figures with huge eyes. But then human society is a very mysterious thing - prone to odd compulsions (like reshaping the skulls of their children) and fearful convictions (such as the belief that processing along lines drawn towards water sources might make the water flow). This intriguing combination of archaeological detective work and anthropology offered a very persuasive terrestrial account for those alien guidance systems - though without entirely dispelling the sense of enigma that hangs over the place. The doggedly credulous won't have gone away completely empty-handed, though. The programme included film of an ancient Andean therapy which involves rubbing the afflicted parts with a live and very squeaky guinea-pig - an alternative medicine which I predict will shortly be available in a crystal shop near you.