Last Night's Television - Storyville, BBC4; Who's Watching You?, BBC2; Coronation Street, ITV1

Carleton Gajdusek was a name unfamiliar to me before I watched Bosse Lindquist's engrossing Storyville documentary, The Genius and the Boys. I learnt that Gajdusek was a brilliant Nobel Prize-winning scientist, born in New York in 1923, who discovered the particles that cause mad cow disease. The programme didn't make it clear whether Gajdusek is alive or dead, since some of the contributors talked of him in the present and some in the past, but the implication was that it hardly mattered, a conviction for the sexual abuse of children having wrecked his once-illustrious reputation.

Most of these contributors, including the neurologist Oliver Sacks, argued that Gajdusek was simply misunderstood, and is/was by no means a paedophile in the darkest sense of the word (and if you wonder whether there is any other sense, one of the eminent interviewees argued with that inflexible logic common among obdurate, elderly scientists with whiskery nostrils, that paedophilia simply means a love for children, and hey, don't we all love children?). Lindquist's skill was in building a formidable case for the defence before unleashing the devastating prosecution, so that over the first two-thirds of the programme I came to believe that rather like Alan Turing, the wartime code-breaking genius, Gajdusek was a decent man persecuted by a warped society. Only towards the end, condemned by his own bizarre self-justifying rants as well as by one of the victims of his sustained and systematic abuse, was he revealed as thoroughly warped himself.

Actually, Gajdusek's weirdness was evident even in boyhood, when he threatened to poison all his classmates in revenge for being bullied. Half a century later, he might have been one of those kids who runs amok in the school corridors with a rifle, but even at the time his threat was taken seriously, not least because he had a vatful of cyanide given to him by his aunt, a famous entymologist, which he used to kill beetles and spiders.

After becoming the youngest-ever person to graduate from Harvard Medical School, Gajdusek went to work at Boston Children's Hospital, and grew obsessed by the killer diseases with no known cure, such as rabies, and acute encephylatis. This work took him to New Guinea, where he responded with what seemed suspiciously like glee on encountering a degenerative brain disease that struck particularly at children. "Jesus Christ, no goddammed bastard on earth has ever seen a disease like this," he wrote in his journal. He insisted on dissecting the brains of the victims on his dining-room table, and someone asked one of the elders of the tribe, among whom cannibalism of relatives was still practised, whether they thought he might be preparing supper. "Why would he eat them, he barely knew them?" was the guileless response, injecting a welcome humorous note into an increasingly troubling story.

Apparently, homosexual contact between boys not yet of marriage age was encouraged by the tribe, and Gajdusek enthusiastically joined in. Later, he fostered no fewer than 57 children and paid for them to move to the United States, where they were educated at his expense. Some popped up here to talk about him in the most affectionate terms, as their hero and saviour. But in 1996 a foster son accused him of abuse, and the cat was out of the bag. Not that Gajdusek was ever able to recognise that he had done anything wrong, histrionically telling Lindquist that sexual contact between children and adults is the most natural thing in the world. How could such a brilliant man be so deluded was the subtext, and there, I suppose, you have most of the world's problems in a nutshell.

Before he was brought to book, Gajdusek was watched for years by the FBI, and there is a reasonable case to be made for the notion that only those with things to hide should worry about the ever-burgeoning surveillance to which we are all subjected, although Richard Bilton argued otherwise in Who's Watching You?.

This was a terrific half-hour documentary. Unfortunately, it lasted an hour, starting with a long and unenlightening tale of a row over CCTV cameras between neighbours in a village in Lincolnshire, which was doubtless deemed irresistible because the village happens to be called Wrangle, but added nothing. Far more interestingly, Bilton showed how by using the internet we all leave a data trail, which can be used for all kinds of nefarious purposes. Of course, the same data trail also catches paedophiles.

Child abuse is one of the few subjects never syringed into soap storylines, and thank goodness for it; Albert Square in particular is a Stygian hell as it is. But thank goodness, above all, for Coronation Street, where not even David (aka Beelzebub) Platt can plan his next evil deed without some good old-fashioned comic relief. Last night it came from Sean Tully, worried that his surname starts with a letter too late in the alphabet, and that all the world's great achievers are early letters, to wit Winston Churchill and Floella Benjamin. Now that's real genius.