Carry on on the psychoanalyst's couch

An English farce about Sigmund Freud fails to appeal to Colin Murphy's ego or his id

Hysteria by Terry Johnson. Presented by B*spoke theatre company. Porject Arts Centre, East Essex Street, Dublin 2. 01 8819613, www.project.ie until 3 June

Sigmund Freud, dying, is confronted by a young woman, an obsessive student of his work. She harangues him until he agrees to revise one of his key case studies with her – that of a woman patient who suffered hysterical paralysis, and recovered memories of sexual abuse by her father while on Freud's couch. It isn't clear whether the woman is real or a manifestation of Freud's doubts over this patient and subsequent writings. But the conflict is real and immediate, and the drama incisive: did Freud's analysis actually damage his patients, and is his work unreliable?

So far, so clear – an erudite dramatisation of some serious ideas, enlivened by a quick wit in writer Terry Johnson's dialogue and strong characterisation.

But then, Terry Johnson's unconscious rises, and subsumes his conscious thoughts. Unfortunately, his unconscious world is entirely populated by the characters of a grand old English farce.

At its nadir, Freud's doctor enters Freud's office to find Freud taking the trousers off a prone Salvador Dalí, while Dalí lies unconscious with a toilet seat around his neck. It looks like Freud is buggering him! The naked girl in the bathroom needs the trousers, you see, and Dalí is unconscious because the naked girl in the bathroom clobbered him with the toilet seat when he tried to molest her. And afterwards Dalí makes a joke about his erection! How Latin!

The woman is naked because she was trying to embarrass Freud into promising to engage with her in a debate about his work, and she's in the bathroom because Freud had to hide her from his doctor. And Dalí is there because, ehm, because he was passing, or something.

What on earth?

Sabine Dargent's set of Freud's office is immaculate. The performances by Darragh Kelly and Alison McKenna as Freud and the young woman, Jessica, are intelligent and nuanced. The scenes dealing with the central drama are sharply written and smartly provocative. But Terry Johnson, for reasons only attributable to some severe unconscious obsession with English comedy, has spliced this drama with a wittering and tedious farce.

Suddenly, each of the otherwise credible characters is running in and out of doors, getting caught in compromising positions and unintentionally cross dressing.

And then there's Dalí, who visited Freud shortly before Freud's death. Johnson uses the Dalí character to fuse the two parts of the play, the drama and the farce: Dalí's appearance and behaviour is resolutely farcical, and Johnson uses Dalí's obsession with the surreal and the unconscious to introduce an element of surrealism into the drama itself, suggesting that all the action on stage may be happening in Freud's unconscious as he approaches death.

That may sound very smart, in a complicated postmodern kind of way, but in fact it's tedious and unconvincing. Terry Johnson gets some good gags about surrealism out of the Dalí-Freud encounter, and some typically smart observations on Dalí's work, but the character's presence on stage is almost always awkward, and the farce and the drama don't knit together.

There is something of a coup de théâtre, in an inventive, low-budget kind of way, when the set morphs into a Dalí landscape at the climax, and director Loveday Ingram manages these surrealist touches very effectively, as well as handling the straight drama well. But it's the conflict between Freud and Jessica that is by far the most interesting aspect of the piece, and the dramatic momentum and credibility of this conflict is thrown away in Terry Johnson's bemusing interludes of farce and surrealism.