Damsels in Distress, Duchess Theatre, London

Remember the joy of rep?

Aficionados of the theatrical marathon are in luck. Offering a welcome alternative to Tom Stoppard's mighty Coast of Utopia at the National, Alan Ayckbourn now directs the West End premiere of his Damsels in Distress, the collective title for a trilogy of full-length comedies (GamePlan, FlatSpin and RolePlay) all set in a riverside apartment in London's Docklands. Both these works by two of our senior dramatists can be viewed in their entirety on Saturdays.

The experiences are like chalk and cheese. Where Stoppard gives you an over-inclusive crash course in 19th-century Russian history, sending the same core characters around an assortment of European locales, Ayckbourn treats you to a vivid reminder of the pleasures of rep. The setting remains fixed, which throws into relief the versatility of the crack company of seven who play a different collection of characters in each piece. When Ayckbourn's plays transfer from his Scarborough base to London, star names traditionally replace some of the original performers. That hasn't happened here, and quite rightly, too – it was the joy of working with this company last summer that inspired Ayckbourn to write RolePlay and turn a planned diptych into a winning treble. The vibrancy and conviction of the cast's teamwork compensate for the patchiness of the writing, where the sequences of inspired hilarity are occasionally propped up by implausible plotting.

If each play is (unlike those in the Stoppard trilogy) genuinely self-contained, there are also recurring preoccupations and stylistic tics. As the title indicates, the focus is on young women who are up against the ropes. To survive, they have to put on a high-risk act, which may well involve taking off clothes and slipping into something a little less comfortable.

The weakest of the pieces is FlatSpin, in which an out-of-work actress goes along with a case of mistaken identity because she fancies the visitor and gets embroiled in an undercover drugs "sting". There are some very good gags. The heroine's pose as a classical music buff is wickedly undermined when the famous blasting choral entry on a record of Zadok the Priest makes her jump out of her skin and slosh wine everywhere. But the ludicrous "comedy-thriller" plot over-relies on the idea that the secret services are exclusively run by bungling amateurs.

The blackest-edged of the plays is GamePlan, where the collapse of her mother's dot.com business and desertion by her father drive Sorrel (Saskia Butler), a 16-year-old schoolgirl, to reinvent herself as Randy Mandy, a part-time prostitute, and to persuade her gloriously gormless school friend (the superb Alison Pargeter) to act as her "maid". With the tubby first customer (Robert Austin) more interested in boring on about his dry-cleaning dynasty and his deceased spouse than in looking at Sorrel's touchingly amateur PVC-clad callisthenics, the comedy is both uncomfortable and moving.

But then the play pushes into an altogether darker area, only to re-emerge too quickly and pretend that it hasn't been there. The offstage sex with this man clearly revolts and traumatises the girl. He, though, obligingly drops dead of a heart attack, allowing the drama to shift its attention to the far simpler problems of disposing of the body and dealing with the police enquiry.

The last piece, RolePlay, returns to vintage Ayckbourn territory: the dinner party from hell. A young couple are planning to announce their engagement at an introductory supper for their prospective in-laws. Her father (excellent Robert Austin) is a Southerner's worst nightmare of a bigoted, mirthlessly joking Yorkshire businessman: his mother (sublimely played by Jacqueline King) is a magisterial lush from Godalming. What makes it worse is that before they arrive, a boxing promoter's moll (Ms Pargeter) has dropped in – quite literally – landing from an upstairs flat on to the balcony as she tries to give her thick, armed minder the slip. Again, there are plot niggles (the hostess gets an opportunity to ring the police about the intruders and doesn't take it), but it's heartening how this gruesomely funny collision of worlds gradually convinces the shy fiancé (a sympathetic Bill Champion) that he must seek a world elsewhere. The zest of the company is unflagging and, with Alison Pargeter's triple whammy, a comic star is born.

Booking to 30 November (020-7494 5075)