Ghost The Musical, Piccadilly, London<br/>A Woman Killed with Kindness, NT Lyttelton, London<br/>Loyalty, Hampstead, London

With the help of some wizard special effects, a notoriously schmaltzy film is transformed into a surprisingly moving show

It was almost a dead cert: Ghost The Musical was sure to be toe-curling, right?

After all, the 1990 film was rife with schmaltz, and with naff special effects once its romantic hero was transmogrified into a crime-solving spectre.

Remember the much-satirised scene where Patrick Swayze's banker-boy Sam and his gal, Demi Moore's Molly, smooch over her squelchy potter's wheel. Or what about the supernatural schlock when Sam's ghost – seeing the villains who've murdered him punished – finally heads heavenwards, apparently summoned thither by Tinkerbell's extended family (a lot of incandescent balls)?

Now Ghost has been rehashed for the West End, with added songs. And the good news is, the musical proves more impressive than the film, because the canny director Matthew Warchus has a wizard technical team, including the illusionist Paul Kieve.

The trompe l'oeils are more thrilling and entertaining. In fact, they're some of the best I've seen on stage. You see Richard Fleeshman's Sam shot dead in an alley, then his soul, in the blink of an eye, rising like a doppelgänger from his corpse which remains sprawled on the ground. When he melts into thin air at the end, you can't see how that's done either.

The video projections (by Jon Driscoll) become dazzlingly snazzy. As we follow Sam and his double-dealing buddy Carl into Manhattan, crowds of city slickers (choreographed by Liam Steel) flow past, while fluorescent skyscrapers swirl around them. Warchus is visibly indebted to director Rupert Goold (of Enron fame), but Ghost is pioneering in terms of West End musicals too, embracing pop-video graphics with panache. Crucially, Warchus has drawn commendable performances from his cast. After a corny opening scene, Fleeshman and Caissie Levy almost become poignant. She's a hopeless potter, but Levy sings a torch song with haunting sweetness. Meanwhile, Sharon D Clarke is a blast, playing the spiritualist Oda Mae Brown with broad comic swagger.

In general, the numbers (by Dave Stewart, Glen Ballard and Bruce Joel Rubin) are a piecemeal medley, ranging from ragtime to rap. Moreover, if you thought Sam's attempts to protect Molly were inept in the film, the denouement in Rubin's stage adaptation is even dumber. He leaves Molly and Oda Mae, surely, facing charges of murder and financial fraud.

In A Woman Killed with Kindness, Thomas Heywood's domestic tragedy from 1603, a well-to-do country gentleman called Frankford treats his adulterous wife with unexpected leniency. "I'll not martyr thee,/Nor mark thee as a strumpet," he explains. Rather, she is banished to a secondary manor house. Expressing surprise at this "mild sentence", the avidly repentant Anne starves herself to death.

Why director Katie Mitchell has chosen to set her production in England in 1919 is unclear. All right, it's before the liberated Roaring Twenties. But if you're transplanting the protagonists towards our time, wouldn't it make more sense to put them in a culture that includes honour killings?

Mitchell's staging, none the less, delicately conveys suppressed unhappiness. We see two women's lives played in adjacent, elegant yet bleak country homes. This is as the action cuts between Liz White's nervous, lonely Anne, and the ancestral pile of Leo Bill's Charles, a reckless young aristocrat compromised by debts who compels his sister, Susan (Sandy McDade), to marry their sworn enemy.

Mitchell does Heywood's drama some favours. Notably, she inserts a silent, wedding-night scene where we see the loss of Anne's virginity has left her bruised. Elsewhere, scene changes convey the passing of time, as servants scuttle up stairwells while the ladies of the two houses drift, like lost souls, in slow motion.

Alas, at other points, Mitchell's textual cuts render sketchy characters even more skeletal, and Paul Ready's brusque Frankford has no heartbroken poignancy.

Lastly, Loyalty is a potentially fascinating debut play by the award-winning journalist Sarah Helm. Associated for many years with The Independent, Helm is married to Jonathan Powell, who was Tony Blair's chief of staff. In Loyalty, a political journo named Laura (Maxine Peake) reveals how strained her home life and select drinks parties at No 10 became, because she opposed the war in Iraq. As the PM's right-hand man, Laura's overworked husband Nick (Lloyd Owen) falls into line with his boss's shockingly unverified claims about weapons of mass destruction: claims that Patrick Baladi's twitchy Tony is later told were nonsense, cynically promoted by Rumsfeld and Bush.

The problem is that Loyalty itself isn't reliable evidence, subtitled "A Fictionalised Memoir". Edward Hall's staging has gripping and satirically sharp moments. But the script is bitty, in need of more nurturing. Peake's Laura comes over as irritatingly smug. Meanwhile, Nick is appallingly indiscreet, letting his spouse listen in on top-secret calls and leaving sensitive documents around for the au pair to read. Tell me it's not true.

'Ghost' (0844 871 7618) to 28 Jan; 'A Woman Killed With Kindness' (020-7452 3000) to 11 Sep; 'Loyalty' (020-7722 9301) to 13 Aug.

Next Week:

Kate Bassett skips to Nicholas Wright's new biodrama, Rattigan's Nijinsky

Theatre Choice

Last chance to catch Michael Grandage's gripping production of Schiller's Luise Miller at London's Donmar (until Sat). Young lovers are ensnared in political machinations, with Ben Daniels as Chancellor. The National Theatre's powerful documentary-musical London Road is back (to 27 Aug), charting the reaction of local people to the Ipswich murders.