Simon Ward reviews in defence of adventurous mothers at The Glitch

As we descend into the underground world of the Glitch we find ourselves in a climbing centre – two large pillars with the tell-tale brightly coloured mouldings on which the intrepid can make their ascent. This is a domain in which Theo (Jack Gray) and Nancy (Lucy Wells) are very comfortable. Their mother was a famous mountaineer and they, too, seem to share her enthusiasm. We soon learn, however, that their mother’s legacy was not only a desire to climb walls with unfeasibly small toeholds. One day when they were young children – Theo just a teen and Nancy 8 years old – they had to face the news that their mother was never coming back. This play is the story of how that trauma shaped the rest of their lives.

Written by Simon Marshall, and partly inspired by real events, it challenges the very idea that parenthood, and specifically motherhood, should be a constraint on how you live your life. But that’s not the message that the children learn at first – their story, as told by the newspapers, is the tragedy of a mother recklessly abandoning her young family for the sake of her dangerous hobby. It’s hard for them to disentangle what they really think and feel from what they are told they should be thinking and feeling. And their father seems to struggle too much with his own loss to be able to help them.

The two actors render all the characters with accomplishment and clarity, but they seem to really inhabit the roles of the brother and sister. Like any sibling pair, there are squabbles and disagreements, but they clearly care for each other deeply. Theo has the big-brotherly instinct to try and look after a little sister who makes it infuriatingly difficult. For it is she that seems to have inherited their mother’s appetite for risk and adventure. Whereas Theo has real-world challenges to deal with – he realises he is gay as a teenager; he forges a career for himself as in the cut-throat world of journalism; he falls in love and plans to adopt a child – Nancy is only ever satisfied by the existential challenge of pitting herself against the world’s toughest mountains.

Director Oliver Savage keeps the action moving restlessly around the space, conjuring up school roofscapes and majestic views, as the two characters chart their different courses through life. The seating is arranged in two rows on either side of the climbing wall columns – there are inevitably moments when the action is not visible, but there is no issue with following the story as the sound is good. This is a funny, heartbreaking, beautiful play. The magic of theatre transforms a tiny basement in Waterloo into a high peak from which you will emerge cleansed, breathing deeply the mountain air.

in defence of adventurous mothers is running at The Glitch, 134 Lower Marsh, London SE1 7AE until Monday 4th August