Following last week’s near perfect episode of Inside No.9 was always going to be an uphill struggle, and unfortunately Nine Lives Kat is a pretty sharp decline. It’s not the worst episode of the series, but it struggles under the weight of its audacious premise. I generally try to avoid spoilers in these reviews, since much of the fun lies in guessing where the story is going, but it’s almost impossible to talk about this one without mentioning the plot, so fair warning – SPOILERS AHEAD!

Sophie Okonedo plays Kat, a troubled yet brilliant detective on the hunt for a missing girl, with a mysterious partner (Steve Pemberton) who constantly appears out of nowhere. If this sounds cliched, that’s kind of the point, as it emerges that there’s more to the story than meets the eye.

A neat inversion of the imaginary friend plot device, as it emerges that the protagonist Kat is a fictional character created by Pemberton, she’s a first draft who’s being relegated to “the bottom drawer” in favour of a more popular, autistic detective (Reece Shearsmith wryly sending up his role in Chasing Shadows). Fighting against her fate, Kat takes matters into her own hands.

Sophie Okonedo is magnificent as ever, bringing real emotion to her character, and the plight of her fictional character fighting for her very existence is incredibly gripping, (if familiar to any fans of The League Of Gentlemen: Apocalypse) but her entire character arc is ultimately waved away in the final twist. Contrary to the co-creators’ own statements on plot twists, it often feels like this episode exists mainly for the twists at the expense of the characters, and a coherent story. I always feel bad when actors of a certain calibre turn up in Inside No.9 only to be given a throwaway part, and here both Siobhan Redmond and Robin Weaver are pretty much wasted in their roles.

In the very best episodes of Inside No.9, the surprises come organically from cumulative reveals of the characters that build to a genuinely surprising finale – Sardines, Lip Service, and Once Removed all demonstrate this perfectly. In an episode like this where the plot is essentially reset after every twist, the mechanics are right at the forefront of the story, and the final rug-pull is less satisfying as a result.

It’s not a total write-off though; The execution is as polished as you would expect, and the multi layered dialogue is as strong as ever. The intentionally cliched writing of the first half is a lot of fun too – yes it’s hackneyed, but there’s enough of the series customary wit and playfulness to make it work, while little asides and touches (like Pemberton jotting down notes), take on a new significance on a rewatch.

There is also at least one genuine belly laugh – Shearsmith popping up over Pemberton’s shoulder and meekly making casting suggestions is a great visual gag. The moments where it veers into horror territory are also wonderfully atmospheric, with a touch of Don’t Look Now and apt references to Stephen King (anyone who’s read The Dark Half will guess where the story is headed after a while), but these moments are too fleeting to make much of an impact.

When an episode of Inside No.9 goes wrong it tends to be for one of two reasons, either the story itself was uninteresting, with an obvious twist, or the writers tried to do too much with their limited running time. Nine Lives Kat is most definitely a case of the latter – it’s a little too ambitious for its own good but I’d still rather have an experimental failure than a plodding safe bet. Seven seasons in, Shearsmith and Pemberton are still playing around with the format and audience expectations, which in itself is reassuring.

Inside No. 9 has returned! Follow my Series Blog here, and catch up now on iPlayer