THEATRE: The iceman cometh

Theatre de Complicite's Mnemonic starts with an introductory talk by Simon McBurney, who conceived and directed the show. It's about memory, what makes us remember, and has lots of (scripted) "that reminds me" digressions. It involves a bit of audience interaction: wearing eye- masks and holding a leaf, we're asked to remember fragments of our own pasts. Everyone finds it quite hard to recall anything specific from autumn 1991.

After thinking about our ancestors, we remove our masks to find that the lecture has become a voiceover, and McBurney is now its masked audience. His mobile phone goes off, and his explanatory conversation about what he's been hearing segues into the show, then becomes a voiceover itself, which then ... suffice to say, the prologue is a very clever nest of Chinese boxes which, unpacked, tell us everything we need to know - to remember - before the theatrical journey begins. Yet for all the invention, visual daring and intellectual substance of the rest of the show, it does not take us much further.

The devised script switches between the discovery in 1991 of a 5,000- year-old corpse preserved in ice in the Alps and a woman's odyssey across Europe in search of her unknown father. The same questions arise: where did he/ she come from? Where was he going and where does she think she will arrive? And how reliable is a narrative of origin and identity constructed from one generation's remove, let alone that of five millennia?

Themes and scenes interlock beautifully, and the performances and images are precise - mountaineers scaling beds; strangers on trains and in taxis; the iceman evoked by a naked McBurney and a collapsible chair. But my abiding memory is of a maelstrom of voiced-over text. Fragments of scientific theories, mobile-phone conversations and television reports are replayed continuously, to the extent that putting the eye-mask back on would have had little detrimental effect.

Memory - and its malleability - is also the central concern of Mike Cullen's Anna Weiss. It is a disturbing play, not least because the memories evoked concern child sexual abuse. Lynn is a nervous young woman who, under guidance from Anna, a private hypnotherapist, has recalled abuse by her father. To move on, Lynn invites him round to confront him with her journal of evidence, which he refutes. In the ensuing battle between claim and counter- claim, the only certainty is that Anna is equally unstable.

Cullen raises many issues about the ethics of therapy. To what extent does the listener instigate, control and validate vague or even fabricated recollections? But Lynn's graphic catalogue of abuses, whether real or imagined, is a serious issue that, in Michael Attenborough's production, is used, somewhat irresponsibly, as melodrama. As Anna fights with the father for control over Lynn's mind, the dialogue consists solely of accusations thrown back as rhetorical questions, or tiresomely shrill variations on "Are you listening to me?" and "Do you hear me?" The performances are raw: as Anna, Catherine McCormack veers from insidious composure to hysterical derangement, while Shirley Henderson's Lynn is a squeaky, jittery child- woman. But Cullen's handling of his material, and Larry Lamb's frantic, credible confusion as the father, provokes an inevitable decision on whose word to believe. By the end, Lynn is not the only one who has been unforgivably manipulated.

Extensive research has gone into Leon London's Leave to Remain, a play about the plight of refugees in Britain. Its writer worked in a refugee hostel, and the programme credits the various organisations and individuals who advised on the production. The groundwork is evident in the authentic specificity of the past traumas of the characters - two Kosovans, a Ukrainian, an Algerian, an Iraqi and an Iranian - and their various ways of dealing with bureaucracy and alienation.

But, while the subject matter has a pressing immediacy, its delivery lacks any dramatic - and consequently, political - force. The set is suitably cramped and drab, with grey concrete blocks for beds, tables and a rooftop. But instead of producing sustained emotional intensity, the confined space only limits the actors' room for manoeuvre and makes their anger and occasional violence seem overwrought. Though the international cast is faultless, it is only Alex McSweeney as Bashkim, a steely, manipulative fixer, who transcends London's representative characterisation.

'Mnemonic': Riverside Studios, W6 (0181 237 1111) to 8 Jan. 'Anna Weiss': Whitehall, SW1 (0171 369 1735) to 23 Jan. 'Leave to Remain': BAC, SW11 (0171 223 2223) to 12 Dec