Last week, we suggested that the then most recent episode of Inside No.9 ­– ‘The Riddle Of The Sphinx’ – might well be the most divisive.

Not because it was in any way the most shocking so far (although it had a number of disturbing moments), and not because – at the other end of the scales – it covered old ground (although it gleefully bathed itself in elements of cliché), but we got the impression that ‘Sphinx’ was the moment when IN9 really exercised the fact that it can now do pretty much what it wanted: no flirting with the old League Of Gentlemen fans with horror and suspense, or being shackled by a twist ending: not that the boys have actually been all that bothered, ever, about doing twists.

Our own perhaps unexpected ending was that Twitter unanimously disagreed with our review: there was no split vote – everyone was declaring it their brand new favourite. Well, they hadn’t seen ‘Empty Orchestra’ yet.

You know how it is with karaoke nights: there are a few who are evangelical about it, demanding that you join them for the ride, and at least one person who’s never experienced the phenomena before, wondering vaguely what all the fuss is about.

It’s tempting to make the same observation about viewers of Inside No.9. While it’s true that one of the main ‘hooks’ of the series is that each episode is contained within a single appropriately numbered location, it’s reasonably rare that an episode is as claustrophobic as this: anyone with a distaste for enforced fun will find themselves nodding (to a beat, presumably) in agreement with Roger’s (Steve Pemberton) moaning concern that the night is just going to be one song after another.

‘Empty Orchestra’ is a half hour of significant emotional heft, having on its playlist such old classics as betrayal, regret and unrequited love.

It may not get the universal acclaim as Season 2’s ‘The Twelve Days Of Christine’, but this is still a powerful ballad, built out of tiny, almost unimportant moments: banal to anyone who might overhear the gossip in the office the next day, but devastating to anyone who is trapped inside the karaoke booth.

Tamzin Outhwaite is a gem as Connie, a cynical and mean work colleague (who happens to be sleeping with her best friend’s fiancé – a ‘Con’ indeed), while Miranda star Sarah Hadland demonstrates Shakespeare’s old line about being little, but fierce. The last time we see her, singing with brand new friends, is a genuine punch the air moment.

Emily Howlett as Janet has the heart of the episode (in more ways than one), and from a narrative standpoint, demonstrates the fallacy of the belief about Inside No.9 being about the twist: when she voices a big reveal to another character, we’re not surprised, but the other character is – and that’s only because they weren’t paying attention.

Elsewhere, Javone Prince is gentle and bewildered as the subject of Janet’s affections, and Reece Shearsmith gives a little essay in bruised selfishness. There are other guest parts who have less than three lines in the episode and are instantly recognisable (‘Well, it’s nearly half past’) and in any case, this episode contains the best (and most emotionally true) performance of ‘I Know Him So Well’ from Chess that you’re likely to see this year.

Aired at 10pm on Tuesday 7 March 2017 on BBC Two.

Buy Season 1 on DVD on Amazon here.

Buy Season 2 on DVD on Amazon here.

Pre-order Season 3 on DVD on Amazon here.

What did you think of this week’s episode? Let us know below…