Afterlife, NT Lyttelton London<br />Dickens Unplugged, Comedy, London<br />The Chalk Garden, Donmar, London

Art mirrors life in Michael Frayn's story of the Austrian impresario Max Reinhardt, yet the drama lacks depth

I guess Michael Frayn couldn't call his new play Half-life. It would have sounded like the radioactive coda to Copenhagen, his previous NT hit about physicists, nuclear fission and Nazism. Afterlife is, rather, a biodrama about the arts and the Anschluss and, specifically, Max Reinhardt. We first encounter the celebrated impresario of Jewish stock in middle age. At the height of his fortunes, before the rise of Hitler, he's being lionised in Germany, Austria and worldwide for his spectacular stage epics – with casts of up to 2,000 actors.

Director Michael Blakemore's Lyttelton premiere is frugal by comparison, yet it gets off to a splendiferous start nonetheless. The Baroque facade of Salzburg Cathedral rolls into view, with soaring white stone arches. Roger Allam's Reinhardt, in a double-breasted suit, bounds forward and declaims the opening lines of Everyman. As co-founder of the Salzburg Festival the showman is – we soon glean – providing a soundbite to persuade the city's archbishop (an attentive David Burke) to sanction a monumental production of the said medieval morality play.

Frayn offers a touch of satire and rapidly introduces a swathe of big issues: artists having to schmooze for patronage; cultural assimilation; latent anti-Semitism; stage directors behaving like mini-dictators; the overlap between art and life. Afterlife then turns into a comparison between the respective demises of Reinhardt and of the play-within-the-play's protagonist. It's half and half in each scene: the impresario's life story and Everyman's, intercut. Both fellows are shown to be unchary spendthrifts who find that they can't take Mammon with them when they're faced with the threat of death – whether that's the Grim Reaper in a skeleton costume or a sour-faced brownshirt commandeering Reinhardt's schloss.

Flicking between rehearsals and the real world, Frayn's elisions are initially amusing and unsettling, a bit like Noises Off but with a menacing sense of doom. What's sorely disappointing is that all the big ideas seem to dwindle as the art-life mirroring exercise becomes increasingly repetitive, as well as selective. Michael Blakemore's cast are admirable, but that can't stop the period costumes looking faintly silly or the rhyming couplets sounding so when they start to invade the 20th-century conversations. Ultimately, Frayn hardly leaves himself room to contemplate what Reinhardt's afterlife might be, and en route so many snippets of Everyman have intruded that his key relationships, with his loyal mistress and long-suffering financial manager, are scarcely fleshed out. Here are the bare bones of a drama, only half coming to life.

As for Dickens Unplugged, this is basically just Dickens Doubly Diminished thanks to the American comedian and director Adam Long, a founding member of the Reduced Shakespeare Company. An eight-year-old, arriving with no great expectations, might be entertained by this ridiculously sketchy biodrama bundled in with absurdly boiled-down enactments of the Victorian author's greatest novels. The five guys on stage, prancing around in stovepipe hats and crinolines, are high-energy but low-grade actors. They're actually better as musicians, playing guitar and launching into Country and Western ditties. Their slacker-style American paraphrases are, now and then, irresistibly preposterous. (Starving Parisian in the worst of times: "I shit you not. She totally took my last old bone.") But mostly this is puerile garbage. How ironic that Long and his colleagues don't know when to stop. They have cut numerous epic works down to size – the Bard, the Bible, Wagner's Ring and Star Wars – but that joke has become mighty tedious now.

What a relief it is to find The Chalk Garden, a small forgotten gem, written in 1956 by Enid Bagnold, now mainly remembered for the novel National Velvet. Revived by Michael Grandage and set in the nicely shabby conservatory of a rambling English manor house by the sea, this is a cranky comedy with a poignantly sad undertow and an edgy element of crime thriller. Margaret Tyzack's Mrs St Maugham – all lace and strings of beads – is a bustling old eccentric who distractedly hires Penelope Wilton's Miss Madrigal as a governess for her granddaughter. Felicity Jones's pert and mocking Laurel is an ill-tended wild child with a murderous loathing for her mother (Suzanne Burden). Madrigal tends to the garden and the girl, but she is hiding a dark past. At points this feels like Arsenic and Old Lace with the potential to morph into Heavenly Creatures.

Perhaps Bagnold was not a born dramatist in the modern sense of capturing naturalistic talk, but her characters' elaborate eloquence sounds almost like poetry and is scattered with pearls of wit and wisdom.

The tempo was rushed on press night and Jamie Glover is unconvincing as the manic manservant. But these are cavils and Wilton gives a tragicomic performance on top form, with buttoned-down tense fragility and glimmers of spiky brio.

'Afterlife' (020 7452 3000) to 16 Aug; 'Dickens Unplugged' (0870 060 6637) to 22 Sept; 'The Chalk Garden' (0870 060 6624) to 2 Aug