THEATRE / Head full of glue: Sarah Hemming on the London fringe, plus Merlin - the Search for the Grail in Edinburgh

WHEN Lesly arrives at her fiance Marty's family home for Thanksgiving, she is greeted by a howl of horror from his twin sister. That's bad enough, but when their mother, smiling sweetly, explains that 'Jackie's hand was holding Marty's penis when they came out of the womb', you might forgive Lesly for heading for the hills. Being a nicely brought-up girl, however, she decides to make the best of it, and stays to be sucked into a household that makes the Addams Family look positively well mannered.

Wendy MacLeod's The House of Yes (the Gate) plunges with a Lynch-like relish into the seamy goings-on behind America's picket fences. MacLeod subtitles her piece 'A Suburban Jacobean Play' and many of the elements beloved by the Jacobean tragedians are there - passion, revenge, incest, murder. Her target, though, is the insularity of upper middle-class America, and she portrays a family where a sense of superiority has allied with rejection of all conventional morals.

Mom had two extramarital fathers for her children; Anthony, her youngest, is a pathological liar and drop-out; while the twins, Marty and Jackie O, have a closeness that manifests itself in incestuous fantasies. Jackie O, at best a spoilt monster, at worst certifiably insane, seems to have been tipped over the edge by the fact that their father 'disappeared' on the day of the Kennedy assassination - all of which has boiled together in her head into a messy glue. The play has a horrible fascination and MacLeod keeps you gripped by the question of whether Lesly will manage to extricate Marty (Jason Watkins) from this mess. In Ian Rickson's production, the women are particularly strong: Dena Davis, as Lesly, manages to be sweetly normal without being cloying, Deirdre Harrison is terrifyingly unpredictable as Jackie O, and Mary Ellen Ray makes a creepy mother. The production goes a long way towards achieving the play's lurid, surreal quality, but it doesn't bring off the hurricane howling outside, which just comes across as corny.

At the Old Red Lion is another tale of hypocrisy and obsessive love, also inspired by the Jacobean theatre - the mood, however, is very different. Rod Dungate's King James' Ear is a meaty, ambitious and very entertaining comedy about James I's destructive passion for the handsome youth Robert Carr.

Dungate creates a court fizzing with jealousy and conspiracy. At the centre is the monarch (Michael Roberts), trapped between belief in his divinely appointed position and lust for Robert, which the Bible he is translating tells him is sinful. Carr (Ben Albu), meanwhile, is torn between his desire for advancement and his love for Sir Thomas Overbury. The whole play is framed by the squabbles between the Court masque designer, Inigo Jones, and Ben Jonson (who bitterly echoes many a playwright: 'I just write language to hang scenery on'). Their battle about style versus content complements the facade- building going on around them.

It's a vivacious play, skilfully knit together, and staged with swagger and inventiveness by Joe Harmston. It is weakened by the female figures, who are very skimpily drawn, and by the imprecision of some characters' motives. But it ends with a scene of real tenderness, which reveals the one true, selfless love in the play.

Gay Sweatshop's Threesome (Drill Hall) offers a quick tour of experimental new gay writing. In Claire Dowie's witty Drag Act, a butch lesbian decides to dress in drag, adding complicated layers to the idea that clothes maketh man (or woman). David Greenspan's Jack expresses beautifully the difficulty of summing up in words the life of a young Aids victim. Three women perched on glittering globes share his story, passing the words round like a musical canon. Phyllis Nagy's Entering Queens is the most interesting: the tale of a budding young lesbian, Ruby, who tries to escape her weird, overbearing mother by becoming a taxidermist. Nagy has a fine talent for creating bizarre, vivid and funny images to tell her story.

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