The show that's all woman

Ask most fortysomething women about extreme behaviour (drinking too much, inappropriate relationships, not speaking to their mother for two years) and they'll have a story. The trouble is we so rarely see it on stage.

So thank you, Simon Stephens, for writing Harper Regan, an astonishingly honest drama of a 41-year-old woman who runs away from her husband and job in Uxbridge to see her dying father up north and ends up having a series of encounters with flawed men. Not only does it contain a career-defining role for actress Lesley Sharp, as Harper, but the play explodes key myths about female sexuality and, more importantly, female anger. Harper gets to glass a racist, sexist man in the pub and have sex with an internet date in a hotel. But this isn't just for shock value.

As the play unravels, we get to understand the transgressive secret Harper is running from - and why her unhinged behaviour might actually be a journey towards sanity.

What's really interesting is that Stephens originally wanted Harper to be male. It was only when the National's artistic director Nicholas Hytner asked why younger writers aren't writing major roles for women that Stephens decided to change her into a woman.

In fact, the playwright reveals, he wanted to give a 'deliberately female structure' to the play, and to explore how women can hold intimate conversations with complete strangers - while hiding the real pain. The drama may seem random and episodic but every character, every motif, resonates at a deeper level. As the layers come off we see a woman in the raw. And it's mesmerising. Harper is no stoical wife or daughter - because this is unapologetically a woman's play.

I defy you not to be moved by the scenes with Harper's clever, spiky teenage daughter, and with her cold-fish mother (terrific Susan Brown) who has compromised in her own relationships. But Harper Regan is never lazily anti-men - this is a play about possible redemption. About putting a family back together, once you face the truth. No one can police any one else's thoughts. We have to trust each other (up to a limit).

What makes it so daring is that it's a male character who gives a fantasy speech about contented old age with the woman he loves, fully aware that he may have blown it. We watch the woman's face for clues. She may forgive him - she may not. Thrillingly, Harper holds the power.

In rep until 9 August. Booking: 020 7452 3000; www.nationaltheatre.org.uk.

Harper Regan
National Theatre: Cottesloe
South Bank, SE1 9PX