All right on the night

Who needs a script? The kings of improv, Theatre Improbable, are back - and this time the critics will get their comeuppance on stage

It's not on record whether an actor has ever bumped off a critic for giving them a bad review, but it's likely to have crossed many an actor's mind, if only in a moment of mischievous speculation.

It's not on record whether an actor has ever bumped off a critic for giving them a bad review, but it's likely to have crossed many an actor's mind, if only in a moment of mischievous speculation.

In Douglas Hickox's 1973 schlock horror film comedy Theatre of Blood, the failed actor Edward Lionheart does just that, driven by murderous revenge to dispose of critics who failed to recognise his greatness by killing them in ways inspired by Shakespearean death scenes.

"It's a fantastically naughty premise, the idea of an actor slaughtering critics," says Lee Simpson, co-founder of Improbable Theatre. "That's why we thought it would be a good idea to put it on stage. The film is both brilliant and rubbish. We like to think our shows are a bit like that as well."

Improbable Theatre is well acquainted with gory deaths: it's best known for providing the puppets for Shockheaded Peter, the ghoulish story of what happens to children who don't heed their parents.

It is also Britain's leading improv company, returning to the National recently with a revival of its 1998 show Lifegame, in which each night the memories of a different guest are acted out in a set of improvised scenes.

Melodrama is close to its heart, partly born out of founder member Phelim McDermott's youth devouring Hammer horror films, and nurtured by a collective imagination. "We've always had a penchant for big theatre techniques, from puppets to different ways of storytelling. Melodrama is rooted in this theatrical style that has absolutely nothing to do with naturalism," McDermott says. "Yet there is something terribly touching in it. When Lionheart gives these great Shakespearean speeches, it almost doesn't matter that he's so bad at it: his passion is very moving."

Improbable thrives on risk. The company began in 1996, with a background in regional theatre and the Comedy Store. Two shows indulged their fascination for sticky tape (70 Hill Lane and Sticky), and they have exploited the precarious nature of improv to ponder the important subjects of other people's lives (Lifegame), their own lives (Spirit) and consciousness (Coma).

Usually, an Improbable theatre production is just that; it's a miracle that it occurs at all. They rarely use scripts, and large parts are made up on the night. "People working with us tend to get very scared because by the end of rehearsals there's usually no script and the production looks dreadful," McDermott says. "But I think learning to let go is a crucial part of the creative process."

This won't be entirely the case on Theatre of Blood's opening night at the National. The trio (the third company member is Julian Crouch) won't be on stage: they are directing a large cast, including Jim Broadbent as Edward Lionheart, who are much more used to the conventions of text and direction. So the company is returning to a rehearsal method McDermott has used before, which he describes as the closest he has got to investing a text with the same energy as improv.

"It's an American technique whereby you record the script and then play it back, and as you do the actors improvise... Each time you play different games with the script and re-record. Come the fifth or sixth time, the actor knows his lines without having ever sat down and learnt them."

Underlying Improbable's insouciance are a profound interest in theatrical ideas and a powerfully intuitive relationship. "They have an instantly recognisable signature, a genuinely original voice, and a rare authority that is the result of long collaboration," says Nick Hytner, the National's artistic director, who commissioned Theatre of Blood. "Their relish for the macabre and grotesque is underpinned by long, serious thought about what theatre is." This is coupled with an intellectually rigorous fascination with the stuff of life itself.

They are also inherently mischievous, hence the decision to stage Theatre of Blood - surely a bittersweet love letter to the egoism, passion and sense of theatre itself in the relationship between the actor and the critic. "It's a celebration of that conflict," agrees Simpson. "Actors and critics really like the film, because it's about them."

On one level, the company's way of working means that a critic's response cannot be definitive. "The only way to do a good improv show is to not care," says McDermott. "If you care too much you kill it. Our shows are like photographs that come slowly come into focus, but they don't do so fully until we are in front of an audience."

'Theatre of Blood', National Theatre, London SE1 (020-7452 3000), from 9 May