Television: Feeling queer? Meet the quacks who don’t want you in the pink

Dr Christian Jessen is as gay as a pair of tan leather shoes or a CD of classical music – which everyone knows is so gay. Well, maybe not everyone. Just the American therapist Jessen met who made a career out of giving "gay-to-straight" therapies. Going through Jessen's suitcase in Undercover Doctor: Cure me, I'm Gay (Channel 4, Tuesday) the therapist – now retired – finds many signs of homosexuality. The Mozart CD isn't just gay, he says; it's not Christian. Religious attitudes to homosexuality fuel many of the "gay cure" therapies Jessen encounters in the southern states of the US and in the UK.

For the one-off documentary Jessen, the out-and-proud TV doctor, offers himself up as a guinea pig for various “gay cure” treatments. (Well, not really. It was more of a stunt than a scientific experiment.) First he goes to Cornell University for a test to define his sexual orientation. It measures his pupils’ response (“the eyes don’t lie”) and his “penile arousal gauge” (that doesn’t lie either) and finds that he is more aroused by pictures of clouds than by images of naked women.

Jessen looks at various pray-away-the-gay church services and $100-an-hour psychotherapies. But the most brutal treatment is also the most disturbing, not least because it was available on the NHS in the UK as late as the 1980s. Called aversion therapy, it gives medicine to induce violent vomiting while the patient watches male pornography. I suspect this documentary, with its jaunty title, started out to expose a modern brand of snake-oil salesman, but Jessen’s anger and frustration gave it some substance.

We have, in any case, been here before. Exposing the burgeoning industry of gay-to-straight "cures" in Out There, his recent BBC documentary, Stephen Fry challenged the so-called therapists every cracked step of the way, questioning their medical thinking, their results and methodology. It made for a more rigorous exposition of the "cure" proposition. Fry's documentary started from the position that homophobia is dangerous and that the "cure" business is part of that. Jessen assumes viewers share his opinion of the ridiculousness of the gay-cure business, which isn't a safe assumption. Rather than accepting the claims made by the "curers" in the phony undercover disguise, challenging them to explain their thinking might have been more effective.

The moment the superb crime series Line of Duty (BBC One, Wednesday) had me hooked was the shocker at the end of the first episode. In hot pursuit of the killer, young DC Trotman was thrown out of the window of a tall building – and there wasn't a single hint, in the run-up to her grisly end, that it was about to happen. Indeed, you'd have bet otherwise, because in the hour-long episode young Trotman had been given a fully drawn, quite intriguing character – a bit racy after hours, full-on chilly professional at work – with potential to last until the end of this week's gripping final episode. Also, Trotman was played by Jessica Raine, one of the stars of the BBC's ratings juggernaut Call the Midwife , so, aside from anything else, she was viewer bait.

But Trotman is just one of many superb, brilliantly played characters in Line of Duty, each always referencing back – and so keeping the plotting tight – to one unassuming key role, that of Ted Hastings (Adrian Dunbar), the boss of the police internal-investigations unit. Line of Duty 's writer and creator, Jed Mercurio, is a fan of old-fashioned keep-'em-coming cliffhangers, with each episode serving up the unexpected.

At the core of this perfectly paced police procedural is an exploration of institutional corruption and human frailty, and how the two are irrevocably interlinked. The six-episode series is the best of the genre on terrestrial TV this year. And while the plot requires leaps – from the murder of a protected witness in episode one to uncovering a criminal gang apparently led by the deputy chief constable – the strong, consistent and credible police characters, each with flaws of their own and so standing on uncertain moral ground, have made it work.

Malcolm Webster poisoned his first wife, attempted to poison missus number two and was about to see off his next wealthy fiancee before he was caught. The 2011 reports of his trial regularly mentioned that the story is “like something out of a Hollywood script”, so The Widower (UTV, Monday), a three-part dramatisation of his life of crime, should have it all. In this week’s opener we see the spendthrift fantasist’s nasty line in wife control. “Take your hands out of your pockets. It looks slovenly,” he snaps at his first wife, Claire (Sheridan Smith).

Fed up with her annoying habit of pointing out his hopelessness with money, Webster (Reece Shearsmith) starts putting tranquillisers in her tea. “Oh, that tastes nasty,” she says before glugging down yet another cuppa, never making the connection (and her a nurse) between the bitter brew and her lapses into a near coma every evening. She accepts his diagnosis of a virus (why?) for her permanent grogginess – “Here, drink up: we must keep you hydrated.” One night, when she’s out for the count, he bundles her into the car, sets it on fire and leaves Scotland for an insurance-policy-fuelled life. Years later in New Zealand he tries his wife-killing method on spouse number two, but she cops on in time.

The problem is that while truth is stranger than fiction, this telling of the story doesn't seem believable – more like a passable yarn than something that actually happened. Shearsmith plays Webster as a creepy weirdo (the real Webster doesn't look like that at all), so your wife-killer antenna is up from minute one. As for the wives, it's hard to believe this Webster would snag one, let alone three, fantastically attractive women. (Fiancee number three is played by Archie Panjabi, the gorgeous Kalinda from The Good Wife ).

For The Widower to make a satisfying drama, it needs to go beyond basic re-enactment and dig deep for some psychological truth. At the very least, a serial-killer drama has to explore motivation: a bad haircut and a facility for lying don't make you a murderous sociopath. Also, the actors playing the wives are fantastic, but their characters don't even attempt to explain why they were so trusting of him.

The Widower is diverting enough, though – incidentally, it was mostly filmed in Ireland, Wicklow standing in for Scotland – and thoroughly watchable, just disappointingly slight for such a juicy story.

tvreview@irishtimes.com