The Weekend's TV: Psychoville Halloween Special, Sun, BBC2<br/>James May's Man Lab, Sun, BBC2

A Halloween treat from the devilish duo

The problem with Halloween these days is that people treat it like Christmas," complained the sepulchral Nurse Kenchington at the beginning of the Psychoville Halloween Special.

"It's lost its real meaning." As she talked she was carefully inserting drawing pins into a batch of fresh muffins for the trick-or-treaters, a little clue as to what she thought its real meaning should be. And although Nurse Kenchington is the villain here, it's pretty clear that, in one respect at least, Reece Shearsmith and Steve Pemberton are on her side: they too want to take the candy out of the occasion and restore the kind of pointed malice that sticks in your throat. Halloween, the commercial festival, may now be suitable for pre-schoolers – a Disneyfied version of the ghoulish. Psychoville Halloween Special most definitely wasn't – blackly hilarious at one moment, and genuinely unsettling the next.

It took the form of a portmanteau film, a genre loved by horror fans because it offers a kind of multiple orgasm of gothic frisson. They're often one-shot affairs, tales of the supernatural, a lot of ominous foreplay leading up to a conclusive spasm as the victim suddenly gets it – in all senses of the phrase. Here the framing device was a location recce for a Most Haunted-style cable show – and as the guileless producer was shown round the derelict Ravenhill psychiatric hospital his guide, a young man traumatised in his childhood by an encounter with Nurse Kenchington, passed on various cautionary tales about its former inmates, all of them well-known to fans of the series.

Mr Jolly stayed true to type, coming in from making seven-year-olds cry to plan an evening of sensuous pleasures: as he tells the escort he books for later in the evening, he's going to have his baked beans first, "so that it doesn't lay too heavy on me stomach." Then he plans to enjoy a couple of horror DVDs and round things off with a bit of commercial sex. Unfortunately the "No tricks, no treats" sign on the door doesn't deter two eerily silent masked children from ringing his doorbell. Eventually – as in all the best ghost stories – Mr Jolly asks for it outright: "Alright, 'Trick' then!" he snarls, "Piss off!", which is naturally the cue for his evening to slide inexorably downhill. Reviewers were begged to give away no substantive details (so as not to spoil things for iPlayer viewers) so I will only say that when Mr Jolly is finally put in the picture, it's in a way that delivers a lovely, unexpected jolt.

Lovely meaning "good to look at", incidentally, as well as delicious, since it's always been one of the virtues of Psychoville that they really get the aesthetics of horror just right. And while it's easy enough to throw everything into shadow and rake torch beams across something grisly, it's much harder to come up with lovely frames like the one in which the reflection of Mr Jolly's face swims into view between the dim shapes of his tormentors through the frosted glass of his front door. Or to devise the dissonant jump from the spangled innocence of a children's television programme to a moment of jangling fright. Shearsmith and Pemberton are copyists of genius, certainly – but they're excellent inventors too.

Psychoville purists may have had some minor grumbles about narrative continuity. Joy, the maniac midwife who dotes on a plastic baby as if it was real, appeared here as victim of a domestic tyrant rather than being the tyrant herself, as she was in the first series, which seemed a little odd. You just had to put it down to the liberties of mischief night, and count your blessings I suppose – which included the return of David, the mouth-breathing serial-killer enthusiast. He and his mother appeared in a classic hitchhiker tale, stranded after their disability three-wheeler breaks down on the way to a Halloween party, to which he'd reluctantly gone as Frankenstein's monster ("I'm sorry," his mother said sternly, "it would have been in bad taste to go as Fred West. It's too recent.") And if this section struck you as a little fairground house-of-horror in its plotting, the framing device then managed to restore a real shock of unease, as the night-vision camera caught odd glimmerings at the edge of the frame. It was a very classy kind of trash – and the best revelation came in the last minute, where it became clear that as well as a perfect Halloween-night entertainment we'd also been watching an hour-long trailer for Series Two.

Inspired by the appalling discovery that eight out of 10 men can't wire a plug, James May has developed James May's Man Lab as "an emergency service, on call to jump-start the stalled evolution of man." It's a kind of grown-up version of Conn Iggulden's bestselling Dangerous Book for Boys – though obviously the phrase "grown-up" only has limited application here. Wearing a parody of the Keep Calm and Carry On T-shirt that read "Get Excited and Make Things", May showed us how to mould a kitchen worktop out of cement, how to serenade a woman and how to defuse a Second World War bomb – pausing momentarily to admire the precision of the Third Reich's engineering skills as he did so. And everyone on screen is having a blast, literally at the end of that item, metaphorically everywhere else. As one of the "feckless, bedwetting, Parmesan-shaving imbeciles" May deplores, I should really hate it. But I just couldn't. They're having so much fun it seems churlish not to smile.

t.sutcliffe@independent.co.uk