The Lord of the Rings, Theatre Royal Drury Lane, LondonInto the Woods, GROH Linbury Studio, LondonThe Pain and the Itch, Royal Court Downstairs, LondonThe Five Wives of Maurice Pinder, NT Cottesloe, London

H um along now, everyone. "Into the woods, it's time to go ... Into the woods, it's time and so, I must begin my journey." Thus Little Red Riding Hood chirrups in Stephen Sondheim's well-known song. And heading into the deep, dark forest proved impossible to resist this week, with two fairytale musicals materialising in the Big Smoke.

First, the Tolkien film trilogy, The Lord of the Rings, has morphed into a three-hour West End extravaganza with tunes. The Theatre Royal Drury Lane resembles a vast cavern of tangled branches, which is initially enthralling, but Matthew Warchus's production is an uneven mix of spectacular special effects and moments of utter rubbish.

Obviously, James Loye's diminutive Frodo (an approximate Elijah Wood lookalike) and his Hobbit pals have much ground to cover on their mission to toss the damned One Ring into the flames of Mount Doom, saving Middle Earth from the Dark Lord, Sauron. Quite a few trudging miles are covered with a chorus line - presumably symbolising life's stumbling blocks - whirling around vaguely in hooded cowls, catching at the wee travellers' heels. This seems a peculiarly lame kick-off for Peter Darling's choreography. Watch out for the fantastically silly druidic disco routines.

As for the set, there's a snazzy revolving fortress, but the Mines of Moria look like Ratners writ large, with one big stalactite fashioned from tacky metal chains. This inspires quite the wrong sense of wonder - ie, wondering if any old passing troll couldn't have cobbled together something better with the near-supernatural budget of £12.5m.

Several subplots are clumsily truncated, the cod-archaic dialogue is titter-inducing, and Andrew Jarvis's white-bearded Elrond confuses ceremonial dignity with patrolling around like a rusty robot, both arms out at stiff angles. The songs keep pointlessly halting the action as well.

Nonetheless, there are bewitching Celtic-going-on-Indian ululations from Laura Michelle Kelly's gilded Galadriel. This is thanks to the input of the folk band Värttinä and their fellow-composer A R Rahman. The acrobatic choreography gets swinging, with the Orcs bounding around like apes on sprung stilts. Peter Howe is lovably loyal as Frodo's sidekick, Sam, and Malcolm Storry's Gandalf sustains authoritative gentleness. The saga's significance also comes over clearly, warning that power corrupts and bringing out an ecological drive in the battle to save the tree-like Ents.

As for the breathtaking special effects, these include Hobbits melting into thin air and the morbid Black Riders rearing nightmarishly out of the shadows on towering skeletal steeds. Regardless of its flaws, this is almost bound to be a crowd-puller.

Simultaneously, the Royal Opera House has mounted a high-calibre studio production of Into the Woods, staged by the choreographer-turned-director Will Tuckett. The more sophisticated ironies and edgy harmonies of Sondheim are certainly a welcome relief as he gets his multiple fairytales in a knowing tangle. Tuckett's use of exit doors is oddly clumsy when Rapunzel and others supposedly get squished by a giantess, but the combination of opera singers and musical theatre actors is a droll delight. Most manage Sondheim's rapid rhyming patter with aplomb while the orchestral strings, under James Holmes's baton, create an oceanic swell of menace and more romantic sentiments.

Suzanne Toase's Red Riding Hood is hilariously horrid, singing with her mouth full of buns as she skips through the forest, brandishing a knife and a fixed smile. Beverley Klein is having a ball as Rapunzel's witchy mother. Anna Francolini also shines as the wife of Clive Rowe's bumbling Baker.

In US playwright Bruce Norris's darkening domestic comedy, The Pain and the Itch, Matthew Macfadyen's Clay is weirdly paranoid about some savage alien creature - maybe a weasel - having got into his dream home. In Dominic Cooke's superbly polished production - his first as the Royal Court's artistic director - Clay and his chic wife Kelly (Sara Stewart) live in a luxurious modernist pad, all snow-white walls. They are also obsessed with raising their toddler impeccably.

This is an explosively funny satire about superficially PC liberals, combined with a creeping sense of horror. Secrets, vicious rivalries and xenophobic bigotry lurk below the surface, and sexual corruption is in the air. Norris's allegory about isolationist imperialist America is ultimately too obvious, and he is discernibly influenced by Mamet and Albee. But en route, Cooke's cast is riveting, with a teasing detective-plot structure and brilliant supporting performances from Peter Sullivan as Clay's cynical, faintly diabolic brother and Andrea Riseborough as his flamboyant Eurotrash tart.

The Five Wives of Maurice Pinder, alas, merely had me itching to leave. What is meant to be startling about Matt Charman's new serio-comedy is that it portrays polygamy as not too bad. Larry Lamb's Maurice is an affable Lewisham builder who loves all his wives, including Sorcha Cusack's' dowdy Esther and Clare Holman's bar-crawling Fay. Then, predictably, the cracks start to appear. Sarah Frankcom's actors are highly commendable and Charman has comic flair, but this drama merely becomes a bore.

'The Lord of the Rings' (0870 890 6002) to 29 March; 'Into the Woods' (020 7304 400) to 24 June; 'The Pain and the Itch' (020 7565 5000) to 21 July; 'The Five Wives of Maurice Pinder' (020 7452 3000) to 27 August. See Exit poll, page 65

Further listening Melvyn Bragg and learned guests discuss fairies: bbc.co.uk/radio4/inourtime; for more on the arts, independent.co.uk/arts