If you’ve read any of the glowing reviews for the current revival of Caryl Churchill’s cloning play A Number, you’ll know all about the extraordinary set. Produced at the Nuffield in Southampton last year and transferred to the Young Vic this week, the intense production places father-and-son performers John and Lex Shrapnel inside a mirrored box where their every move is reflected infinitely. The audience is split into four around its edges, and watches the action through one-way glass. In between scenes, the mirror effect is reversed and the audience sees itself reflected.

The reason that Caryl Churchill is Britain’s best living playwright is that her work is endlessly enquiring and peerlessly intelligent. When she wrote this play about the subject of human cloning – which had its premiere at the Royal Court 2002 with Michael Gambon and Daniel Craig as its cast – she avoided the obvious option of writing about how bad the idea of cloning is, and instead opted to explore its individual consequences. By doing so she came up with an unforgettable image of humanity in all its pain and anger.

Is there more than one Michael Longhurst? As sometimes happens in theatre, a rising young director seems to be everywhere at once. His calling card is the modestly universal Constellations. Directed with clarity and simplicity, Nick Payne’s romantic two-hander with multiple narratives has travelled from the Royal Court via the West End to New York, before touring the UK and heading back to London this week. Longhurst may need to clone himself in order to be in two places at once: his production of Caryl Churchill’s A Number is also opening at the Young Vic.

Kafka and Jones, the names above this little shop of horrors, would be a marriage made in off-kilter theatreland had the Czech genius written any plays. He didn’t, so Nick Gill has made a well-shaped drama out of the assembled fragments of which The Trial consists.

Coming-of-age comedy, moonlit romance and a gentle folk soul: can this really be Eugene O’Neill? The master of darkness makes a surprising departure with semi-autobiographical 1933 work Ah, Wilderness!, which visits staple tropes – addiction, family strife, responsibility and regret – with a marked lack of rancour. Like its youthful protagonist, world-weary cynicism is a mere pose, abandoned in favour of beguiling, hopeful innocence.

How do we respond to a tragedy of infinite mystery? We investigate, we speculate, and we seek to impose meaning, to produce a story that safely contains unfathomable horror. However, those hoping for such reassurance via a traditional theatrical narrative in Bush Moukarzel and Dead Centre’s Lippy will come away disappointed. This darkly absurdist piece floats searching, fundamental questions, but answers came there none.

For those who never saw Samuel Beckett’s favoured performer Billie Whitelaw on stage as indomitable, buried-alive Winnie, peculiarly happy days are here again with another once-in-a-generation actress facing what Dame Peggie Ashcroft called “a ‘summit’ part”, the female equivalent of Hamlet. Juliet Stevenson makes you think not so much “what a great performance” as “what a towering masterpiece of a play” – and how often do star interpretations even of the big Shakespeare roles prompt that kind of reaction?

Mike Bartlett is the most prolific and talented British playwright to emerge in the past decade. Not only has he created large-scale epics in a variety of styles — from the science-fiction fable Earthquakes in London to the Shakespearean King Charles III — but he has also delivered a series of short plays — My Child, Contractions and An Intervention — in which he hones down the story into sharp shards of powerful emotion. Running at about 55 minutes, Bull is one of these.

British theatre company 1927 celebrate their 10^th birthday next year. Over this nearly-decade they have produced just three shows (plus a reimagining of The Magic Flute for Berlin’s Komische Oper). If that seems a little like slacking then you’ve obviously never seen one of their creations. To say they are meticulous is true, but also fails to reflect the sense of imaginative excess, of abundance, that pulses through everything they make. Animation, live action, music, song, dance and mime all have a place in their world.

A Martian, a Spitfire and a flatulent penguin are the unlikely ingredients for The Way Back Home, English National Opera’s first foray into the colourful world of children’s opera. And if those don’t sound like enticement enough, be reassured, at only 45 minutes long this really is a child-friendly taster of a genre that doesn’t always get the best press when it comes to accessibility.