Betty Blue Eyes, Novello, London<br/>London Road, NT Cottesloe, London<br/>Moonlight, Donmar, London

Cameron Mackintosh's latest is a let-down &ndash; but a musical about the Ipswich serial murderer is an unlikely triumph

First we had War Horse, Michael Morpurgo's novella dramatised by the National Theatre, with some of the most breathtaking puppetry you'll ever see. And now here comes Post-War Pig.

Sorry, I mean Betty Blue Eyes: a new West End musical. Based on Alan Bennett's comic screenplay A Private Function, this is directed by Richard Eyre and stars an animatronic porker.

The setting is a Northern English country town, with brick terraces emitting curls of black smoke, though pink-tipped clouds suggest sunnier fun to come. This is Austerity Britain, 1947. But despite stringent food rationing, the town's burghers (led by David Bamber) plan to treat themselves to a royal wedding banquet. They're fattening up an unlicensed sow.

Obviously, they mustn't get caught by the Food Ministry's fanatical Inspector Wormold – Adrian Scarborough in leather trenchcoat and specs, looking like Penfold from Danger Mouse crossed with Himmler. What Bamber's Swaby hasn't bargained for is the audacity of Gilbert Chilvers (Reece Shearsmith), who purloins the premium hog, Betty.

The storyline keeps Betty under wraps for too long. When she is revealed, lolling in a wheelbarrow, she is rather splendid from the neck up: a downy, coquettish creature, eyelashes fluttering and ears quivering. Alas, however, Betty doesn't have working shanks – four legs no good – so if you're hoping for farcical chases round the Chilvers parlour, you'll feel badly let down.

Composer George Stiles and lyricist Anthony Drewe offer droll rhymes and some pleasing, old-school English harmonies (folksong, church choir-ish, music hall). Gilbert's social-climbing wife, Joyce (Sarah Lancashire), has one jazzy, fantasy number, her kitchen invaded by top-hatted gents and showgirls wafting ostrich feathers. A wartime flashback is an excuse for swing dancing, with girl-whirling GIs (choreographed by Stephen Mear).

Still, the evening left me disgruntled. The book (by Ron Cowen and Daniel Lipman) falls flat, retaining only a few of Bennett's funniest lines. The terraces remain essentially drab,

and Shearsmith isn't going to raise any roofs as a singer. This production has socialist leanings (with a "Fair Shares" protest march) while also being patriotically royalist (with vintage newsreels of Elizabeth and Philip). Betty Blue Eyes clearly hopes to profit by coinciding with Britain's bunting fest for Wills and Kate, but it's all a bit lame.

Meanwhile, at the NT, London Road is a new piece of music theatre, directed by Rufus Norris, which takes the 2006 serial killing of Ipswich prostitutes as its subject.

What sounds like luridly distasteful melodrama turns out, in the hands of writer Alecky Blythe and composer Adam Cork, to be an inspired documentary musical. Blythe's book and lyrics are drawn, verbatim, from taped interviews with dozens of Ipswich residents, particularly the apprehended murderer's shocked neighbours on London Road – a residential street that had become a hang-out for streetwalkers. Members of the media circus who reported on Wright's arrest and trial also feature.

The collated interviews include some fascinating insights into the effects of mass fear and suspicion, on women and men. There's also an unexpected happy ending, tinged with moral complexities. A bevy of residents celebrate the neighbourhood's new community spirit and best-front-garden competition, sweetly and comically delighting in their blooming petunias, but (in some cases) expressing zero sympathy for the girls now six feet under.

What's musically thrilling is how Cork sets the words to music, retaining every "um" ,"er" and inarticulacy, and brilliantly drawing out the rhythms and cadences of vernacular chat. Ordinary speech just seems to slip into song with, say, a piano and woodwind rippling softly underneath. Short repeated phrases are built into richly layered choruses.

Cork is not, of course, the first composer to be alert to local speech patterns, but London Road is the most excitingly innovative musical I've heard or seen. An excellent cast (including Kate Fleetwood and Howard Ward) effortlessly take on multiple characters to create a remarkably detailed social panorama. Don't miss.

Harold Pinter's 1993 play Moonlight is haunted by death – deaths both past and imminent. In this semi-phantasmic portrait of a dysfunctional family, a ghostly young woman hovers at the foot of her father Andy's deathbed, her feet the colour of red clay. As if drifting into each other's minds, Pinter's estranged parents and children exist in limbo between the real and imagined: a blue-carpeted chamber ringed by light in the Donmar's revival, directed by the quietly excellent Bijan Sheibani.

Andy (the gaunt David Bradley) and his incommunicado son Fred (a near-derelict Liam Garrigan) are both largely bedbound and stuck in ruts. Yet everybody is hard to pin down, partly echoing Pinter's own social mobility from working-class East End to Holland Park intelligensia.

At once unsettling and comic, Bradley's crotchety patriarch is highfalutin' and poetical one minute and has a mouth like a sewer the next. His long-suffering wife Bel (Deborah Findlay) sits nearby embroidering, cool as a cucumber then suddenly looking daggers at him – a frozen moment that's almost demonically powerful.

The feverish banter between Fred and his brother, Daniel Mays's Jake, is more tiresome. They play a habitual game, pretending to be part of some elaborate civil service or Le Carré-style spy network. They are, we glean, terrified of talking directly about their lost sister or their father. This isn't Pinter's best play, but Sheibani's cast are compelling, letting you glimpse a desperate, buried tenderness between the lines.

'Betty Blue Eyes' (0844 482 5170) booking to 22 Oct; 'London Road' (020-7452 3000) to 18 Jun; 'Moonlight' (0844 871 7624) to 28 May

Next Week:

Kate Bassett on Little Eagles, the RSC's new play about the space race

Theatre Choice

The King James Bible gets a cover-to-cover reading at Shakespeare's Globe on Bankside, right, starting with Genesis and Exodus today (and ending 25 Apr). Dropping in for a bit is, incidentally, permitted. Or hurry to catch Rory Kinnear's caustic Prince of Denmark in Nicholas Hytner's often startling Hamlet, briefly back in rep at the NT (to Fri).