Review: Damien Love on Inside No 9

If you have a taste for claustrophobia and awkward, uncomfortable situations - for sticky dramas that force a random cast of strange characters together in a place with no escape, some of whom don't want to be there at all, rubbing elbows with others who want to be there far too much, and all of them heading toward crisis - this Thursday is a golden night. ITV has The Leaders' Debate (8pm). The seven party leaders are perhaps dreaming of Borgen, but it will probably turn out more like a bright frozen nightmare version of Hitchcock's Lifeboat, with Natalie Bennett in the role of most-likely-to-get-eaten, and the studio audience cast as a passing shoal of angry piranhas.

If you're still conscious by the end of those two hours, though, do your TV a massive favour and flip to BBC Two, where lurk the true current masters of sticky claustrophobia, Steve Pemberton and Reece Shearsmith, with the latest of their unexpected tales from Inside No 9. If there is one thing that honestly deserves not to be missed this week, this is it.

The second series of Shearsmith and Pemberton's anthology show, in which each week a new story unfolds inside a different "Number 9", got off to a fine start last week, with an episode that cunningly replayed the sardines situation that launched the original series last year. Instead of a group of partygoers reluctantly crammed together in a wardrobe, a bunch of strangers shared the close horror of having to sleep beside each other in the cramped couchette of an intercontinental train. It was uneasy, coarse, excruciating, grotesque and hilarious, with black humour dolloped on top, and an unsettling secret twist hidden beneath - in short, it was what all the best Number 9s have been.

The greatest thing about the anthology format, however, is the most obvious thing: it's different every week. Entering Number 9, you never know quite what you're going to get. While it might seem like Pemberton and Shearsmith have imposed severe limitations on themselves with the restricted conditions of their short, single-location stories, the opposite is true. These tales might be confined within four walls but, in there, feeding off the intense atmosphere, the writers are exploding in all kinds of directions.

Certainly they are with this week's episode, which sees them stretching into territory utterly unlike anything the pair have ever tackled in the past. To say much about the story, which is called The 12 Days Of Christine, would spoil it, but it's safe to state some facts. The setting is, mostly, Flat 9 in a humdrum high-rise. And there we find Christine, an ordinary young woman, played quite extraordinarily by Sheridan Smith.

It is directed again by Guillem Morales, the Spanish filmmaker who did a beautiful job exploring the corners of that train compartment last week. But it exists a world away from last week's jaunt. There are jokes, but they are mostly the passing jokes people share in real life, and it's not really a comedy. If there's a bleak, black humour working here, it's of the rarest sort, the kind that is filled with sympathy and tenderness. There are ghostly jumps and flickers, but it's not really a horror story, either, except maybe it is. But it knocked me sideways, in ways I wasn't expecting at all, and which I can't get out of my head. It is, by a shattering distance, the best use of 30 minutes on TV this week.