Jerusalem, Royal Court, London

This one you have to see. Mojo writer, Jez Butterworth, has made a storming return to the British stage this year. Following his comic morality of suburban betrayal on the edge of the forest in Parlour Song at the Almeida, he goes right to the heart of things in Jerusalem, a dystopian hymn to hippie-dom on St George's Day in darkest Wiltshire.

The play is given the full treatment – 15 fine actors led by the peerless Mark Rylance as Johnny "Rooster" Byron, a generously wooded outdoor setting by Ultz, and a perfect production by Ian Rickson. It's the best British rural play since David Rudkin's Afore Night Come a very long time ago.

And it combines elements of the best of Alan Ayckbourn with the zonked-out zaniness of that great woolly "Archers on acid" saga, The Warp by Neil Oram.

Rooster gives some advice to his six- year-old son, who has visited the encampment with his mother: "School is a lie. Prison's a waste of time. Girls are wondrous. Grab your fill... Don't listen to no one and nothing but what your own heart bids. Lie. Cheat. Steal. Fight to the death. Don't give up. Show me your teeth."

There's no balancing argument to this manifesto, and one of the accusations hurled at Rooster – and not resisted by him – is that he's a drug supplier to minors. Butterworth and Rylance have created one of the great mischievous monsters of modern theatre, a Lord of Misrule on the same scale as Falstaff or Jeffrey Bernard, a Pied Piper of protest and disaffection.

Rooster has a hilarious story of how he was kidnapped by four Nigerian traffic wardens in Marlborough town centre. He'd got drunk and relieved himself in public, that's all. There's no room for excess in modern life any more.

Gerard Horan's publican turns up for his stash of "whizz" dressed as a morris dancer. And one of the gang, Danny Kirrane's plump xenophobe, Davey (nice Shakespearian name), reckons that the local BBC television programme has lost its way by reporting stories across the border in Wales.

It's key that Rooster has worked as a painter, and his sidekick, Ginger – beautifully done by Mackenzie Crook as a moonwalking zombie with delusions of adequacy – as a plasterer. The new estate, which they are protesting against vociferously, is at least a potential source of income. But the authorities are on Rooster's case and his days are numbered, just as the Queen of the May plaintively evokes a landscape of pastures green and dark satanic mills.

This farewell to the buried life of the Avebury Circle, the mysteries of Stonehenge and the legends of old Albion is also their last, defiant resurrection. Rylance is magnificent in a hugely demanding role, and restores one's faith in the power of theatre to make a really beautiful noise and on a scale that is both epic and potentially popular.

To 15 August (020 7565 5000; www.royalcourttheatre.com )