Do not see this weird concoction if you think that the National should confine itself to nurturing live dramatists and reviving dead ones, as it’s doing very well with Howard Brenton’s Never So Good and Thomas Middleton’s Revenger’s Tragedy. But you might give 90 minutes to the piece that Katie Mitchell and her company have derived from Dostoevsky’s The Idiot if you believe, with me, that Britain’s most important theatre should sometimes take risks, play with strange ideas, experiment with new techniques.

Not that . . . some trace of her is the failure I feared when an abstruse programme note told me that the company was using “dog chews to create the sound of a thousand cannibalistic fairies”.

What had that to do with The Idiot or with the wonderfully dark Emily Dickinson poems often injected into the production? Were we about to be riveted by the brilliant Mitchell whose revival of Euripides’s Iphigenia in Aulis was so imaginatively powerful, or maddened by the wayward Mitchell whose Seagull left Chekhov’s characters half-invisible behind directorial razzle-dazzle?

A bit of both. Instead of narrative clarity we get a version of The Idiot so impressionistic that those unfamiliar with the original novel will think they’re dreaming or drunk. Why bother to mention Totsky or Ganya when you’re not told who they are? And the emphasis on video effects means that the company spends an awful lot of time scrambling in the murk in order to take photos of each other. It’s distracting, it’s irritating - but, when you see some actors’ faces projected on to the large screen at the back while they converse below, it serves a purpose.

The evening’s big success is Ben Whishaw’s Prince Myshkin, who looks as well as sounds the mix of sensitive Candide and caring Candide he’s meant to be. It’s hard to twig that his friendship with Jamie Ballard’s tough Rogozhin becomes a fatal rivalry, because that man’s name is barely heard, but at least we get some sense of Myshkin’s pitying, self-sacrificial love for the unhappy, corrupt young woman who has divided them, Hattie Morahan’s Natasya.

And at least we’re not merely seeing actors blundering in the dark. We’re observing the crannies, corners and twisting corridors of people’s minds, the caverns and catacombs of their souls as they try to discover who they are, what they want, where they’re headed. In other words, a fragmented production gives us the fractured feel of Dostoevsky himself.

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