TWENTY-FIVE years after writing Otherwise Engaged - and 21 years after its acclaimed London premiere - Simon Gray revisits the territory to see how his central character, Simon Hench, originally played by Alan Bates, has shaped up. Not well, it would seem. The publisher has become an ex-publisher. His wife has become his late wife. The phone, which was once attached to an answering machine, has been Simply Disconnected.

Hench still tries to keep the world at bay, but it keeps strolling in - not through the hallway of his London home, but through the French windows of his place in the country - bringing problems, making demands, wanting responses.

Hench remains strenuously non-committal, still forgets everyone's name - yes, that old joke again and again - and still wants nothing more than to sit and listen to music. (He hasn't the energy for Parsifal these days: he prefers a recording of his wife singing in church.) Most importantly, Hench is still Alan Bates.

He slopes round his living-room in sweater and trainers, disarming interlopers with grimaces, nods and furrowed eyebrows. He is a master at saying "Ah". When he does commit himself, it's to correct someone's logic or use of language. It is one area in which he can be sure that he is right.

The 21 years have set Bates's eyes even further under the eyelids, burying his feelings, and allowing greater scope behind his engagingly crumpled features for evasively blank responses. Bates exploits the contrast between his mental agility and emotional inertia to the full. It's a riveting portrait of phlegmatic charm which continually hints at spiritual paralysis.

Gray's plays have had a hard time recently keeping up with the level of off-stage drama that he chronicles in his diaries. (Stephen Fry left his last production.) The diaries have a lurid, swirling momentum that is horribly plausible; this free-wheeling energy doesn't extend to his stage characters. Hench is a largely passive figure, reacting to whatever crisis walks in. The situations Gray presents him with have an old-fashioned Shaftesbury Avenue feel to them. Real life, evidently, supplies Gray with better plot lines than the ones he gives his alter ego.

Hench's dowdily finicky brother, Stephen (Charles Kay), arrives with news that a pupil has accused him of sexual abuse. Hench's former best friend, Jeff (Gawn Grainger), pitches up on the way to a book launch with his alcoholic wife (Rosemary Martin), to explain that he is now a very successful author. A ghostly, stuttering young man (Benedick Bates; yes, Alan's son) bursts in, wearing a shabby suit with dirty cuffs, and pulls out a gun. The revelations that follow are more theatrical than dramatic.

This is a slight, sketchily conceived sequel to a more significant play. Gray's elegantly precise ironic humour always entertains us, while never convincing us that he is that interested in any character except Hench. Even Hench would be less interesting to us than the playwright himself - whom we have come to know so well from the diaries - if it weren't for Bates's multi-layered performance.

The contrast between Simply Disconnected and Marina Carr's new play Portia Coughlan, between covert English irony and raw Irish emotionalism, couldn't be stronger. The latter was commissioned by the National Maternity Hospital in Dublin and paid for entirely by contributions from a group of women. They have got their money's worth.

In the Abbey Theatre's overwhelming production, directed by Garry Hynes, we face shocking events in an unmistakable environment. The play is set in a small town in Ireland, and the inter- connected families of the Coughlans, Scullys and Doorleys speak in richly individual dialect.

It opens with Portia's husband, Raphael (Sean Rocks), finding Portia drinking brandy at 10am: "Tin a'clache i'tha mornin' an' ya'are ah ud arready." It's Portia's 30th birthday. As strikingly played by Derbhle Crotty, she's a frighteningly destructive and skittish woman, who drinks, sleeps around, and neglects her young kids. She's haunted by the death of her twin brother, Gabriel, who died when he was 15. This tragedy - and the events that lie behind it - possesses its own fearful logic, revealed through the explosive family rows. The dialogue is violently candid, with particularly virulent contributions from Blaize Scully, the 80-year-old grandmother (Pauline Flanagan). Carr's harrowing play has the scale and anguish of a myth, and the immediacy of a contemporary anecdote.

It's 250 years since Three Hours After Marriage was first performed at Drury Lane, where it ran for only seven nights. Considering that it was written by John Gay, Alexander Pope and John Arbuthnot, this satire on a man who is a collector has become a curio itself.

The RSC has handsomely rectified this neglect with Richard Cottrell's delightful revival. The text emerges as remarkably unencumbered, though no one is credited with "a new version by". Cottrell and designer Tim Goodchild successfully relocate Three Hours in the late Victorian era. Entering the Swan Theatre, you encounter a set that you could spend the evening exploring. Goodchild has designed a spectacular private museum with hundreds of curios in display boxes and drawers: shells, clocks, insects and stuffed animals that include a bear and a giraffe.

Three Hours, which runs for well under that, follows the events immediately after the marriage of Dr Fossil (Clive Francis) to the cunning Susannah Townley (Jane Gurnett). It's an excuse for some exotic character acting, which this company seizes. Fossil's niece, Phoebe Clinket (Alison Fiske), is a boomingly voluptuous poetess and Dr Possum (John Quayle) a slimily pedantic lawyer. As the poutingly effete Plotwell, one of the wife's would- be lovers, Richard McCabe dresses up as a Polish professor and captures the spirit of Groucho Marx. Finally, he and his rival Underplot (Adam Godley) disguise themselves as an Egyptian mummy and a crocodile in one of the funniest scenes you are likely to see.

At the Manchester Royal Exchange, American playwright Alex Finlayson follows up her award-winning Winding The Ball with Misfits, which takes us behind the scenes during the making of the The Misfits, the 1961 film starring Monroe, Gable and Montgomery Clift. Monroe's husband, Arthur Miller, wrote the script. Here, Finlayson finds a telling fable about the sexes that has resonance far beyond simple showbiz legend.

A series of deft elliptical scenes builds up a tough, witty study of addictive and/or obsessive personalities, quite unwilling or unable to comprehend Monroe. When, towards the end, the journalist W J Weatherby asks her for an opinion, she says: "Gee, my big chance. My lucky day."

Gregory Hersov's imaginatively fluent production moves between trailer, hotel room, hospital and desert, while the large cast are boldly convincing. As Marilyn, the radiant Lisa Eichhorn moves between enchantress and emotional wreck, in a performance that leaves you with a deep sense of hurt.

Theatre details: Going Out, page 14