If you think about it, how else would a stage adaptation of Inside No. 9 begin other than an unannounced smash cut to black? Comedy duo Reece Shearsmith and Steve Pemberton have made a lifelong career out of staying one step ahead of their audience, keeping them in the dark and making them squirm. And with Stage Fright, the theatrical translation of their nine series anthology, they start as they mean to go on.

After a satisfyingly grisly skit about the deadly consequences of disrespecting theatre etiquette, the pair greet us with a welcome and a warning. We are of course in the New Theatre, where it is said lurks the ghost of Bloody Belle, an actress who died tragically during a performance of La Terreur de l’asile (Terror at the Asylum). Mentioning her name three times is all it takes to summon a frenzy of possession and murder for any hapless cast occupying the stage.

Not that that fases Pemberton, who dismisses the whole thing as bollocks and encourages the crowd to invoke the vengeful spirit to (apparently) little effect. In a show packed to the gills with in-jokes and ‘for the fans’ nods, starting from the top with an original conceit is a wise move that marks the production as its own entity, keeps the tension humming as to when the other shoe will drop, and gives an easy in for any attendees who aren’t on their 6th rewatch to find every bronze hare.

That said, if you are such a fan, Stage Fright will be absolute catnip for you. The iconic title music is plucked in real time by onstage violinists as the dusty shaft of light from No. 9’s beckoning door is projected across the curtain. Our first half is a largely straight restaging of the season 4 episode ‘Bernie Clifton’s Dressing Room’, following former comedy partners Tommy ‘Cheese’ Drake and Len ‘Crackers’ Shelby as they reunite for one last gig. It’s intercut with a reworked nod to the season 1 standout, ‘A Quiet Night In’, a completely wordless episode in which two incompetent cat burglars attempt to rob a luxury house. There’s even a sight gag paying homage to the show’s pilot ‘Sardines’, which naturally earnt rapturous applause.

Incompetent the stage thieves may be, but silent they are not; after all, how else could they banter with their ‘mystery guest’ hostage? Our kidnappee for the evening, singer Will Young, was an unexpected delight, game for all the improv the duo throw at him and chucking in some ad libs of his own that clearly took Shearsmith and Pemberton by surprise. Given the slightly catty shade thrown at Lily Allen throughout the show (a note which is rather soured by some of the revelations on her recent album), maybe this is a sign for the pair to give pop stars a fair shake?

We dip a toe into horror in the first half; the second, however, is where we take the full cold plunge with an entirely original setup. As a troupe of actors prepare for a revival of La Terreur de l’asile, tensions rise between our leading lady - a pop-star gimmick hire - and her resentful cast. Meanwhile, something otherworldly is lurking in the wings. I won’t spoil anything here, but I will say the cast, reprising their roles from the West End, square up brilliantly to Pemberton and Shearsmith’s gung-ho commitment to both the silly and the scary. Miranda Hennessy nails it as an actress utterly out of her depth, perfectly making every wrong move from the overwrought RP accent to the visible cogs working as she considers her next gesture or expression. Gaby French’s timid and deferential theatre attendant innocuously lays the groundwork for our big twist to hit, and Sarah Moyle and Bhav Joshi are doing the absolute most as weary luvvie and overweening bit parter respectively.

What stands out most here, though, is the sincere love of genre and medium; the Hammer Horror delivery, the incorporation of live camera feeds both a nod to The Blair Witch Project and modern Jamie Lloyd-style directorial choices; the hints of The Woman In Black in the incorporation of the audience and stage architecture into the scares. What sets Shearsmith and Pemberton apart as writers of both comedy and horror is their recognition that both have the same root; the tension of incongruity, of something being not quite right. Whether that tension is released in a laugh or a scream, their writing never feels like one genre wearing the other’s skin. Instead, they weave their commonalities together out of an abiding respect for both - and it’s why they’re the only team that can go from Blair Witch to Busby Berkeley and still have the whole thing feel cohesive.

My mind goes back to ‘Bernie Clifton’s Dressing Room’. Using this episode as a framing device is a particularly ingenious touch, not just because it’s a showcase of their serious dramatic talent, but because it serves as one of the TV show’s more metatextual commentaries. Shearsmith and Pemberton have been on our stages and screens in one form or another since 1995. Like their Cheese and Crackers counterparts, they have nothing but love for the game, but they’ve seen the comedy landscape shift tectonically around them in the three decades since. Where our real life pair differ, however, is their ability to constantly push and challenge the limits of their medium to keep up. They’ve already proven their aptitude for translating the show into other formats, as seen in their Ghostwatch-indebted Halloween special ‘Dead Line’ or covertly supernatural gameshow ‘3 by 3’, and with Stage Fright they’ve captured that magic again by embracing the same spirit of experimentation. Cheese moulders and crackers get stale - Pemberton and Shearsmith show no signs of doing either.