‘You’re such a journalist,’ says Vicky Featherstone when I ask her whether 27 is going to ruffle feathers among scientists and Christians. The play is, after all, about a crisis of faith in a convent provoked by a scientist’s request to study the nuns in his investigation of Alzheimer’s and dementia.

‘It genuinely asks the questions,’ says Featherstone, artistic director of the National Theatre of Scotland. ‘What does the struggle with faith mean, is there a God and what is the pursuit of science about? The play is not provocative to either side, but it paints the picture that neither pursuit is easy.’

27 brings her back into the rehearsal room with Abi Morgan, currently being celebrated as the writer of The Hour with Dominic West and the forthcoming Thatcher bio-pic The Iron Lady with Meryl Streep. They first worked together when Featherstone ran Paines Plough and the director is hoping to repeat the success of plays such as Tiny Dynamite and Splendour. ‘She’s incredibly open as a writer, but she also has a strong vision,’ says the director. ‘It means she produces something with context and ideas, but is open to the play being shaped by the actors in rehearsal.’

The play is inspired by a scientific study of 678 nuns by David Snowdon, which he described in Aging with Grace, an exploration of how a convent life can influence health and longevity. For Morgan, it’s a chance to explore the pressures on scientists to be business-minded and on nuns to be part of the secular world. ‘It’s a beautiful piece about aging, loneliness and faith versus science,’ says Featherstone, who visited a convent as part of her research. ‘Abi is able to write really rich characters, who all change in some way. They’re real people, so it’s exciting, dynamic – and very funny as well.’

Royal Lyceum, Edinburgh, Fri 21 Oct–Sat 11 Nov.