Mother Teresa Is Dead, Jerwood Theatre Upstairs at the Royal Court, London

The excellent actor John Marquez seems to be cornering the market in boorish working-class bigots. He was transfixing at the National recently playing a knee-jerk racist soccer fan, spoiling for a fight, in Roy Williams's Sing Yer Heart Out For The Lads. For the same director, Simon Usher, Marquez is equally impressive now in the role of a slightly more intelligent version of that bullying bigot in Mother Teresa is Dead, a new drama by Helen Edmundson set in India.

His character, Mark, arrives in the Madras village fizzing with sweaty irritability, as though the subcontinent had been created with the specific purpose of affronting him with its sweltering heat and allegedly suspect taxi drivers. To be fair, he is under enormous pressure. He has travelled from England to India in the hope of being reunited with his wife Jane who, seven weeks ago, disappeared without warning or any indication of her future plans.

She has now been discovered in an unstable state on the streets of Madras and has been taken under the protective wing of Frances (Diana Quick), an English expat in her mid-fifties who has herself left unresolved family business back in Blighty.

The tense, worried-sick Mark wants to unravel the mystery of why Jane suddenly abandoned him and their five-year-old son in favour of working at a shelter for street kids in an Indian city. And everyone would like to uncover the secret of what is contained in the plastic carrier bag that she clutches with such nervy determination, and why she has talked of a baby.

A character who takes such a drastic step is a handy device for asking fundamental questions about the purpose of life and the gross inequalities on this planet. Yet despite a compelling performance from Maxine Peake, who brings a concentrated moral intensity and ghostly post-traumatic stillness to the part of Jane, there is insufficient texture in the characterisation, and not enough back-history. "India does strange things to people," declares Frances, but in Edmundson's stilted, plodding play what it chiefly does is make folk sound like debating positions rather than psychologically complex persons. Letters from charities have, it seems, driven Jane to a state of mind where her worries about her own son (whether he'll learn to read as quickly as he should, pass exams and go to college etc) feel guiltily luxurious in a world where Albanian orphans pace the bars of their cots like animals or where poverty-stricken Indian villages smother newborn girls because there is no money for dowries.

We never get to the bottom, though, of why Jane has come to see love of family and active compassion for humankind as mutually exclusive. She has deserted her little boy, who thinks that it is his fault that she left. The play does not seem to take into account exactly how much that severance discredits her idealism in advance.

Glamorous Harry Dillon plays Srinavas, the handsome, young, Oxbridge-educated Indian who runs the children's shelter, and who puts moral and amatory pressure on Jane to forge a new life of charitable service in India. Again, though, this character's views are compromised before they can have due impact by his smarmy sexual vanity, his selfish mixed motives, his pleasure in goading Jane's husband into ugly outbursts of lame-brained racism, and his evident preference for abstract righteousness over practical love. Little Englander Mark may be in many ways a limited man with some unfortunate instincts, but I suspect that it's with his beleaguered confusion and incredulity that audiences will most identify.

To 13 July (020-7565 5000)