Shoes gently tapped, the audience settles into the intimate space of The Black Forest as Katy (Alex Brain) carefully explains what will follow. We are to be ready for a story within a story, a tale of bravery and the Big Wave, of a king and a knight, and of fearsome dragons and how to defeat them.

We are introduced to the music makers and their instruments and then the tale begins.

Fifteen-year-old Katy and her big sister Hannah (Alex Simonet) live by the sea with Paul Williams (Lizzie Grace), Katy’s imaginary dog. There are pleasures – swimming, dancing, fish-finger suppers – as well as challenges.

Katy is on the autism spectrum. Her day-to-day life is a scaffold of rules and rituals that, if respected, keep her feeling safe. She’s a straight talker with a need for truthful answers to her many questions – personality traits that attract cruel responses from some of her classmates.

When newcomer Ryan (Tom Colliandris) moves to the coastal town after the loss of his best friend, the sisters reach out to him. The trio’s connection is transformational and finally satisfies Katy’s passionate yearning for a friend.

We Live by the Sea comes to Adelaide’s Fringe Festival after sell-out seasons in Edinburgh, New York and London, brought here by Patch of Blue and Greenwich Theatre in partnership with Australian producer Joanne Hartstone.

All four performers are outstanding, and make good use of simple props and lighting as well as projected film sequences to bring the seaside home to life.

Live vocals and music from band Wovoka Gentle enhance the action onstage to help build a clearer picture of Katy’s struggles with sensory overload.

This is a gripping, emotional and honest glimpse into the life of two young women with a lot on their shoulders.

Katy’s story makes the point that it’s “time to do a different kind of thinking”, time to dip our toes into the ocean of experiences outside our comfort zone. After all, even the biggest dragons can be slain if you have someone fighting with you.

Four stars

We Live by the Sea is showing at The Black Forest (Royal Croquet Club) until March 19.