I'm still unconvinced that possibly – probably – the greatest 'new writing' theatre in the world should be joining what can undoubtedly now be called the bandwagon of Roald Dahl stage adaptations. But whoever produces it, you can't deny a terrific show when it comes around. And this one – better than Charlie and the Chocolate Factory and not quite as brilliant as Matilda – is terrific. It also boasts a lot of new writing by Irish writer Enda Walsh whose manic imagination has grafted a narrative onto Dahl's portrait of married sadists. Whether John Tiffany's dark and visually stunning production will hit box office pay dirt for the Royal Court in the same way as Matilda has for the Royal Shakespeare Company remains to be seen. The chances have to be less than they would have been had The Twits been a musical. Still, with Chloe Lamford's ingenious O-shaped set, and two utterly brilliant performances by Monica Dolan and Jason Watkins as the couple whose marriage must have been made in hell, this production has the visceral imagery of watching someone's escaped nightmare.

Dolan and Watkins – tweedy roly-polys both – look like the grotesque offspring of a public school house master who has mated with a toilet brush. They are also the embodiment of Quentin Blake's illustrations, only made more upper class. Watkins's red beard is a personal hygiene emergency; Dolan's teeth, an oral calamity. But what's scary is the void where most people have at least a modicum of kindness.

And tormenting as they do a family of monkeys who are made to dance for the Twits' pleasure, the final production of the Court's Revolution season has more than a whiff of allegory about it.

The monkeys are the oppressed, the Twits are despotic rulers, and the three hapless fairground workers who are invited to the Twits' Home County estate to take repossession of the fairground that their hosts stole years previously – well, that's Walsh's slightly convoluted plot. It relies too much on the stupidity of childlike adults for my liking. But you need victims of the Twits' ferocious cruelty and Wurlitzer Boy, Yorkshire Terrier Man and Tattooed Fortune Teller Lady fit that bill very well. They also compensate for the lack of children in the show. The ones in the audience were utterly transfixed by the cartoonish violence that is meted out by the couple, much of it to each other. Saucepans are never used for cooking.
The suggested lower age limit is eight, which might be a little young for the more nightmarish moments. But then, as Dahl knew very well, there is nothing more satisfying for a child than having survived something genuinely scary.