Jerusalem, Royal Court Downstairs, London<br/>The Apple Cart, Theatre Royal, Bath<br/>Bassline, Barbican Centre Car Park, London

The Theatre Downstairs has turned into a wooded dell. Leafy trees arc over the stage and a girl in a satin slip stands by a recently axed trunk, quietly singing William Blake's "Jerusalem", as if it's a mournful folksong: "And did those feet in ancient time ...".

Throbbing rock music drowns her out, blasting from a ramshackle silver caravan. A modern-day bacchanal is suddenly in full swing: a mêlée of hooded youths dance around like raving lunatics.

Just as abruptly, it's the morning after and everyone has vanished, except a pair of po-faced County Court officials, clutching clipboards. They stare at the festive wreckage and slap an eviction order on the door.

Time is running out for Mark Rylance's Johnny in Jez Butterworth's new, weird and rather wonderful, disaffected English pastoral, Jerusalem, directed by Ian Rickson. Johnny is an ageing, drug-dealing "gypo" who used to be a daredevil biker and hero at the local fairs. He has lived in this wood for years, but he's now becoming a bête noir: an annoyance to a neighbouring new estate when he goes on his wild benders. He might even be seriously dangerous.

Primarily, Jerusalem is a very funny comedy about rustic wasters. Rylance lurches out of his caravan like an addled clown – or a tattooed, hung-over hobgoblin – his pelvis still gyrating, spliffs sprouting from his boots. With a touch of the warlock, the Pied Piper and Peer Gynt, he draws idling lads, young lasses and nutters to his den. He sells them whizz and spins delirious impish yarns about how he was born in a black cape, with a bullet between his teeth, or how he once chatted with a passing giant, just off the A14.

Rylance's comic timing is a delight. He just steers clear of milking his gags as he oscillates between macho swagger and nervy mumbling. Mackenzie Crook flails amusingly as well, as his spindly sidekick, Ginger, alongside Alan David as a batty old professor, and Tom Brooke who plays a sweetly gormless teen. Rylance also has startling tenderness, and volcanic rage at the law-enforcing Goliaths who threaten to raze his home.

Butterworth's script is rambling at points, and the cast's West Country accents could be pinned down better. But the surreal digressions and the moments of cursing black magic – tapping into age-old superstitions – are terrifically bold. The way treachery and sinister brutality lurk in the shadows is gripping too. The adolescent girl we glimpsed singing at the start has, we glean, been missing for a week, and her abusive step-dad wants retribution, or a scapegoat.

If Jerusalem is a darkening contemporary vision of England's green and pleasant land, The Apple Cart is a period piece/prophecy about our nation. That is to say, George Bernard Shaw wrote this rarely revived political satire in 1928, but set it "in the future".

The programme notes accompanying Peter Hall's production – in his Bath summer rep season – proclaim that line after line might have been written yesterday. Truth be told, though, this piece isn't astoundingly topical, and Hall's staging doesn't attempt to look up-to-the-minute.

As Shaw's fictional British PM gathers with his ministers at King Magnus's palace, His Majesty's private secretaries are perched at their desks with Bakelite phones. Barry Stanton's Boanerges, a union leader and new cabinet member, strides in dressed like a Russian revolutionary. Then, in a tweedy three-piece suit, the Prime Minister (James Laurenson) brandishes an ultimatum for the King to sign, insisting the monarch give up his political powers of veto.

Shaw was sharply prescient in some respects. He sardonically anticipated, here, the reduction of Britain to America's lapdog, and the rise of huge corporations, slipping politicians into their gold-lined pockets. But, in truth, the main reverberations are with the distant past, with the constitutional crisis looking like a variation on the Magna Carta, and with Magnus directly echoing Shakespeare's history plays.

The Apple Cart is a minor curio, yet it's enjoyable to see it given this airing by a perky ensemble. Charles Edwards's debonair Magnus is an entertainingly canny royal, keeping Janie Dee as his slinky mistress on the side.

For Bassline, the focus narrows from big political debates about this sceptre'd isle, zooming in on east London today – indeed, more precisely, on the inner-city neighbourhood immediately surrounding the Barbican Centre. Graeme Miller's promenade piece (for BITE:09) is a multimedia installation rather than theatre, strictly speaking. But wend your way down into the subterranean bowels of Car Park No 5 and you find yourself in a strangely haunted kind of art gallery, accompanied by a stately Purcell-inspired ground bass, somewhere in the distance. A line of translucent banners stretches away into the darkness, shimmering with monochrome photographs of the nearby streets and estates. Victorian alleys and faceless tower blocks are endowed with a silvery, melancholy beauty as you wander though this ethereal world, chasing time-lapse images of strangers vanishing round corners.

The snippets of local people's voices – recording their impressions of the area – may seem frustratingly fragmentary. Go with the flow, though, and Bassline captures both the transience of city life and a sense of ghostly, layered history.

'Jerusalem' (020-7565 5000) to 15 Aug; 'The Apple Cart' (01225 448844) to 1 Aug; 'Bassline' (0845 120 7550) to 26 Jul