The queen of the whodunnit has never gone away, but with John Malkovich playing Poirot and two radical stage adaptations, it’s no mystery why a new generation is falling for her

The interior of St Martin’s theatre in London is a luscious red, with ornate wood panelling picked out in coral and gold. Piano music floats gently across the auditorium. It feels slightly like a shrine, which in effect it is, since from 1974 it has been home to just one play: Agatha Christie’s The Mousetrap.

The world’s longest continuously running play transferred there from the Ambassadors theatre next door, where it had opened on 25 November 1952, to mainly favourable reviews. Seeing it now, the audience takes a knowing part in a ritual: it is a museum piece, lovingly tended by refreshing the cast each year, but framed by a reverence for the past and Christie’s reputation.

The plot, surprisingly perhaps, is based on a shocking real-life case of child abuse and death and rooted in a profound sense of horror. It springs its twists like a well-oiled machine. The audience, though mainly grey-haired and touristy, is not exclusively so – an indication of the broad popularity of the piece. Even at a midweek matinee, there are few empty seats. Next year, there is a nationwide tour starring Gwyneth Strong (who played Cassandra in Only Fools and Horses) while the old warhorse continues in the West End.

Facebook Twitter Pinterest Shocking case … Lisa Barry and Matthew J Wilson in the 50th anniversary cast for The Mousetrap in 2002. Photograph: Tristram Kenton/The Guardian

The production is, nevertheless, an old-fashioned pleasure – and a million miles from the BBC’s approach to Christie. This Christmas, for example, John Malkovich will play Poirot in The ABC Murders, without a moustache or a Belgian accent. It is also a long way from the stage version of Witness for the Prosecution, now running at London County Hall, which has notched up a year of performances, shows every sign of vigorous life, thanks to its atmospheric site-specific setting and its emphasis on the psychological truth of its characters. Then there is a new, multi-viewpoint version of one of Christie’s best Miss Marple novels, The Mirror Crack’d, which is being adapted for the stage for the first time by Rachel Wagstaff.

Christie would no doubt be delighted by the interest in her work in the theatre. She worked hard to get her breakthrough as a playwright, finding success in the 1950s only after a long series of false starts. “Of course, I knew that writing books was my steady, solid profession. I could go on inventing plots and writing my books until I went gaga,” she wrote in her autobiography. “Writing plays seemed to me entrancing simply because it wasn’t my job, because I hadn’t got the feeling that I had to think of a play – I only had to write the play that I was already thinking of. Plays are much easier to write than books – because you can see them in your mind’s eye, you are not hampered by all the description that clogs you so terribly in a book and stops you getting on with what’s happening.”

Facebook Twitter Pinterest A profound sense of horror … Agatha Christie. Photograph: Popperfoto/Getty Images

She was impelled to write plays partly out of competition with her glamorous older sister Madge, who had a play in the West End before her, and partly because other people kept adapting her novels in ways that she didn’t much care for. Witness for the Prosecution, which she wrote in 1953, after the success of The Mousetrap, was her proudest achievement as a dramatist. She wrote a total of 29 plays and their success has for many years skewed the figures on work by female dramatists. In 1982-83, for example, 650 plays were produced nationwide, of which 42 were by women – with 22 of these by Christie. For long periods, she has been the only female writer with work being performed in the West End.

Current stage productions spring from a decision on the part of the Christie estate. Not so very long ago, her plays were a repertory and touring staple. “People had become accustomed to a certain kind of Agatha Christie,” says James Prichard, the author’s great grandson, now CEO of Agatha Christie Limited. “They didn’t take her seriously enough as a writer or as a playwright. We felt there was the possibility to raise the standard to something more special.”

Facebook Twitter Pinterest The new cast 2018-19 cast for the West End production of The Mousetrap. Photograph: St Martin's theatre, London

Women have come to the fore in this attempt to see Christie through new eyes. Just as Sarah Phelps has revitalised the stories for TV, the director Lucy Bailey gave Witness for the Prosecution a jolt of theatrical electricity.

She had loved the novels from childhood – and like a child, she says, still adores the suspense. “The sense that something violent is going to happen, the fear that keeps you in tension,” she explains. But she also found deeper currents to explore. “A lot of Christie is about predatory relationships,” she says. “She writes about deception, betrayal, philandering men, liars. And about revenge. You can talk about her as pure narrative, but it is a bit like the way that David Lynch develops his work; he takes narrative and then provides this whole subtext which is very disturbing. The undercurrents in Christie are also disturbing.”

In the venal Romaine Vole, Christie creates one of the complex female characters who animate so many of her stories – in settings that explain the society in which they must operate. “The play is a serious excavation of the British justice system,” says Bailey. “It is also a piece of strong entertainment but that doesn’t mean that Christie hasn’t got a sense of inquiry about the establishment, the class system, the club of men who make these judgments on people’s lives. She argues that the passing of law is suspect when it is founded on such class prejudice and misogyny.”

Facebook Twitter Pinterest Plot twist … John Malkovich as Hercule Poirot in the BBC adaptation of The ABC Murders. Photograph: Charlie Gray/BBC/Mammoth/Charlie Gray

To make these themes come alive for a contemporary audience, Bailey has, with the estate’s permission, modernised some of Christie’s dialogue. “This is to honour her, to show how good, fresh and relevant her pieces are,” she says.

Wagstaff, who is adapting The Mirror Crack’d, directed by Melly Still, for a production that opens at Salisbury Playhouse before touring next year, has been allowed an even freer hand. “We have played with form,” explains Wagstaff, previously behind stage versions of Sebastian Faulks’s Birdsong and Paul Gallico’s Flowers for Mrs Harris. “We replay the murder from the various perspectives of the different characters. In this way, we are looking at the fluidity of memory.”

Like Bailey, Wagstaff has adored Christie since childhood. “I’ve always had a real love for the books, and for the TV adaptations starring Joan Hickson as Miss Marple, or David Suchet as Poirot.” But in shaping one of Miss Marple’s adventures into a play, she has filled out the story of the little old lady who is a better detective than the best of the police. “Why is she as she is? Why isn’t she married? What is this incredibly clever woman doing in this little village? Would she have been head of Scotland Yard if she had been around today? We are looking at that and her feelings of loss and regret.

“For me, the dream aim of creating an adaptation is that you are utterly honourable to the thing you love – because you wouldn’t be doing it if you didn’t love it - while creating that brand new piece of art if you dare.” Wagstaff believes boldness is vital to staging Christie: “You don’t just want audiences to think ‘Oh I know what this is going to be.’”

Just as Witness for the Prosecution roots itself in profound questions of how we judge people, so The Mirror Crack’d draws its power from its examination of grief. This can get lost in glitzy adaptations such as the 1980 film starring Elizabeth Taylor as Marina Gregg, a fading Hollywood star on the verge of a comeback. But Wagstaff hopes to assert the story’s humanity. “The story is about how we are all affected by the shadows cast by loss and how we live with those present but absent losses.”

Facebook Twitter Pinterest Humanity … Elizabeth Taylor in the 1980 film of The Mirror Crack’d. Photograph: Allstar/EMI/StudioCanal

At the heart of the plays, however, is another quality that may explain why Christie is as popular as ever. “There is such a strong human need to impose order and it is what she does so well,” Wagstaff says. “All of the characters are damaged and have their own stories and are therefore suspects. There is always a rational explanation for why this thing has happened and why people have behaved as they do.

“I think we crave that in life, which is why we enjoy the whodunnit and that satisfactory ending. We are living in uncertain times, frightened by the mess our world is in. It is a way of stepping out of your life and having that glorious, perfect, ordered explanation of why life has been as it was.”

Certainly, as far as Lucy Bailey is concerned this is one reason why Witness for the Prosecution looks set to continue its run. “One of the actors said that this is the best job in the world because you walk across the foyer after a show, and you see people smiling. It is a very joyous experience, because we are in such a mess and everyone feels in this limbo. She offers something with clear frameworks. A society of rights and wrongs and ways forward.”