The Selkie myth is ripe for retelling with a modern feminist spin, and BoxedIn Theatre have managed to do that in a deeply touching way – one that is rooted in the story, and avoids the obvious danger of getting bogged down in polemic. For those unfamiliar with the original tale, it's about a seal who can shed her skin to become a human; in the classic version, she is then prevented from returning to the sea by a man who hides that skin, before she recovers it and escapes to the ocean, never to return to land.

In this update, Jim is a fisherman and Sarah a surgeon, and they have a daughter, Grace. Jim is happy with his life as it is – but Sarah is missing the opportunities available in the city. Gradually, that pressure to be who she wants to be pulls her away from her family.

To explain what has happened, Jim tells his young daughter that her mum was a selkie who donned her seal skin to rescue him from a storm, but cannot now return for twenty years. As Grace grows up, her exuberant friend Ana encourages to think that there is more to her mum’s disappearance than the story she fervently believes… and so they set out on an adventure to discover the truth.

Grace Thorner gives an exquisite performance playing Grace as a child and teenager. Her energy and facial expressions are just perfect, and there’s one moment when she isn’t the focus of the scene, yet her reaction to her parents dancing is a thing of beauty. The music by Oli Savage is beautifully understated, only occasionally imposing itself to let you know how well it is supporting the story; the storm in particular is very nicely done. We’re in a tent in the square outside the Symposium Hall, which is lovely and brings a warmth all its own, even if the traffic noise is occasionally at odds with a quiet coastal environment.

I like the way that a fairly standard tale of family breakdown is told with the traditional genders reversed, without any fuss over the fact that this is what they're doing. But there is a world of hurt stemming from Sarah's decision which the production glosses over, something I can't imagine happening if the roles were the other way around. And sometimes there is a little jarring between the realism of the production and the fairy-tale nature of the story; they just about pull it off, though they could afford to lay off the exposition a little bit and trust the audience to work it out for themselves.

The thing about myths like the Selkie story, is that they suggest a world where we can be one thing or the other – in contrast to the multiple traits and contradictory impulses that we are really made up of. To the Ocean, by allowing Grace to be the focus of the piece, lets us experience her parents’ tales separately as well as her own. As she says: “there’s more than one story”.