Loyal Women, Royal Court Theatre, London

In 'Loyal Women', Gary Mitchell has a powerful and potentially devastating theme. Other playwrights, notably Martin McDonagh, have suggested that the attraction of the IRA could be the feeling of masculinity it confers on men who can make up, with violence and rhetoric, their sexual and emotional failings. In this play, the Women's Ulster Defence Association likewise compensates for vanishing family and social ties.

On a council estate where the only occupations seem to be TV-watching, sex, drink and assault, Brenda battles to keep her demoralised household going. She has kicked out her ex-convict husband, Terry, after his drunken fling, but she still looks after his bedridden mother. To Brenda's teenage daughter, Jenny, membership of the WUDA offers a diversion from caring - when she can be bothered - for her baby.

Gossiping about neighbours with suspected Catholic sympathies and planning reprisals, the women achieve a closeness and sense of purpose absent from the rest of their lives. But, in the weeks before Christmas, the nature of their activity breeds distrust. Brenda is forced to become treasurer of the local WUDA branch because anyone who volunteers for the job is suspected of embezzlement. Maureen, the head of the group, wants to hand over her job to Brenda; another woman, furious at being passed over, becomes angrier when told why. What seems to be an alternative family is, in reality, a more dangerous duplicate.

Josie Rourke's cast - particularly Michelle Fairley as Brenda, Lisa Hogg as Jenny and Clare Cathcart as Brenda's rival - are impeccable in their bitter and defeated demeanour. But the production lacks that vital theatrical spark that goes beyond realism, a deficiency most obvious in the writing. Real-life WUDA women may well express themselves in soap-opera clichés, but that's no excuse for Mitchell to do so. There were no giggles on the first night, but I think a less partisan audience will be amused when Brenda says, in a lull during the shouting, "This isn't a good time for me.".

And the play is frequently confusing on major matters. We don't know how long Terry has been out of prison (an important plot point), or what Brenda feels about him. The conflicting emotions she avows seem implausible, as do the reason for his imprisonment and his explanation of it.

Loyal Women has a nice sound effect - the scenes begin with Christmas carols that fade into martial music - but the verbal music of the play is too often off-key and out of tune.

To 13 December (020-7565 5000)