Happy Days, Lyttelton, NT, London <!-- none onestar twostar threestar fourstar fivestar -->

If you look on the bright side...

The last time Fiona Shaw and Deborah Warner collaborated on a piece by Beckett (with Footfalls in 1994), it resulted in a famous run-in with the playwright's estate. Warner had reassigned some of the lines and used two distinct locations within the theatre, rather than one, for the compulsive shuffling of the central character.

Her striking new production of Happy Days is unlikely to rouse the estate's wrath. But, while it obeys the letter of the law, it is characteristically radical in spirit. In its investigation of the play, it has taken nothing for granted.

This is immediately apparent in Tom Pye's design, which locates Winnie's mound in a vast rubble-strewn landscape of broken concrete and stone on which a battery of bright lights beats down fiercely, sending wafts of heat out into the Lyttelton stalls. In a manner you can't precisely pin down, it puts you in mind of both Iraq and global warming. The symbolism of Winnie's existential predicament - buried first up to her waist and then up to her neck in parched earth - is thereby placed in a wider, realistic-seeming context of global apocalypse.

Wakened by the bell, Shaw's Winnie takes some time to remember where she is, peering blearily into the audience. Then she shakes out her locks, tips back her head and declares: "Another heavenly day," comically hoisting the rapturous adjective over her appalling circumstances.

In Shaw's busy, witty portrayal of the character, Winnie's daily rituals with the items in her bag become routines in the theatrical sense of the word; jaunty, mischievous performances whereby she struggles to distract herself from despair.

She hums the Archers theme tune as she takes her fingers for a walk round her mound. Having polished off the dregs of a bottle of medicine, she not only sends it crashing over the mound in her husband Willie's direction (as Beckett stipulates) but cheekily parodies its promise to bring "instantaneous improvement" with little strong-man poses to show off her biceps.

It's arguable, though, that this Winnie is too archly aware of the audience and that this diminishes our sense of her terrible loneliness. When she says, towards the close of the first act, that she has the "strange feeling that someone is looking at me," her puzzlement at the eerie possibility of onlookers sounds phoney, as she has been playing up to the public throughout.

It's possible, too, that Shaw's undisguisably keen intellect does not find an ideal outlet in this part. The best Winnie I have seen was Rosaleen Linehan in Karel Reisz's production for Dublin's Gate Theatre. She played her as a suburban Irish Protestant, anxious (even in these extreme conditions) to keep up middle-class appearances, and she endowed Winnie's penchant for the quarter-remembered literary quote with an air of would-be gentility that was both very funny and poignant.

As performed by Shaw, Winnie is, for my taste at least, over-alert to the ironies of trying to look on the bright side while being stealthily entombed in earth, and her ragged Irish delivery tricks out the lines with an excess of knowing inverted commas. If you had taken Linehan's Winnie to see a production of Happy Days, she would doggedly have denied that it had anything to do with her life. Shaw's Winnie would have far less of a problem in identifying.

Where Shaw succeeds marvellously is in the way she highlights the heroine's desperate dependence on her neglectful, masturbating husband Willie (Tim Potter), to whom she is also hilariously condescending. The production had the unusual effect of making me want to see the proceedings from his unwholesome side of the mound.

And the shorter second act boasts all the benefits of Warner's insistence on the reality of Winnie's plight. The teeth she once fussed over are now black with decay. The sun-scorched head emits screeches of protest and harrowing panic, or splutters deluded love songs.

This production by Warner is a bracing new look at one of modern theatre's supremely eloquent images.

To 1 March (020-7452 3000; www.nationaltheatre.org.uk)