Theatre review: Proof

Mental illness and prime numbers both seem to be theatrical memes at the moment, and they're coming together at the Menier as Polly Findlay revives David Auburn's Proof. Robert was an exceptionally gifted mathematician in his youth, but the last ten years have been blighted by an unspecified mental illness which left him delusional and unable to work on coherent theories. His younger daughter Catherine (Mariah Gale,) although unable to finish her studies as she's been caring for him, may have inherited some of his mathematical genius but could that also mean she's inherited his madness? In the opening scene she worries about this threat to her sanity as she has a conversation with her father (Matthew Marsh) but she may already have her answer - as he's been dead for the last week.

In the days before and after Robert's funeral, the extremes of Catherine's mind come into question again as one of her father's former students, Hal (Jamie Parker, obviously drawn to characters with that name,) discovers a notebook in what looks like Robert's handwriting, but which Catherine says she wrote. Its contents prove a theorem mathematicians have been puzzling over for decades. Is Catherine the latest genius in the family? Or is she simply claiming authorship of her father's final masterpiece?

The apparent beauty of mathematics has always eluded me but it's enough that Auburn's characters feel it intensely and are endlessly excited about the possibilities - and the play never dwells on the actual details of the equations they're getting excited about. There's also a sort of race against time going on - the play suggests that mathematicians either come up with something amazing before the age of 25 or fade into obscurity, and Catherine has just reached that age, with Hal a couple of years past it. Among a lot of lighter moments within the drama is a picture that starts to build of ageing mathematicians as wild party-animals desperately clinging on to youth in the hope that it might inspire a breakthrough that'll put them in the history books.

Mariah Gale has always had a slightly distant, otherworldly acting style that here strongly suggests Catherine might have good reason to fear for her sanity; there's certainly a paranoia at work as she interprets her sister's (Emma Cunniffe) requests to join her in New York as an attempt to get her sectioned. There's some heartbreaking moments to her performance, particularly in a flashback to the realization that her father's recovery has been temporary and his new notebooks are full of gibberish. Parker is charming - perhaps too charming for Catherine's good - as Hal, in a standout performance. And Findlay's unfussy production tells the story quietly but with momentum.

Proof is a absorbing little story even if, like me, you consider maths essentially a foreign language. There's something universal to the story of lights that shine brightly but not for long. And therefore something appropriate to the fact that in tonight's performance Gale and Parker had to carry on through the final scene in sudden, unexpected twilight when a power cut took out half the lights.

Proof by David Auburn is booking until the 27th of April at the Menier Chocolate Factory.

Running time: 2 hours 5 minutes including interval.