Matty’s mother is packing his suitcase for him to leave home. In a room full of cuddly toys in all the colours of the rainbow (plus plenty of neon shades), she counts pairs of trousers, t-shirts, socks, off a checklist. She’s matter-of-fact, impatient, over-brisk and chatty, talking to Matty through the bathroom door. Talking to herself, as Matty’s not answering back.

Matty comes out of the bathroom with a towel around his waist and another for a cloak, a showercap on his head. He looks like a total superhero, it’s hilarious. Matty’s 19, and leaving home for the first time. He has Down’s Syndrome, and needs to learn to look after himself.

We warm to Matty immediately. He’s playful, imaginative and much gentler than his mother, Odette – subtle and well-timed in his few words and measured gestures. Where she is rushing around, multitasking, scolding, laughing and reminiscing, he is content to stand, unfazed, observing and dreaming. Actors Heather Williams and Nathan Bessell have a great dynamic together, though Williams (also directing) occasionally seems a little nervous or preoccupied tonight, fluffing some lines and slightly off-tempo. The heartfelt script is conversational enough in style that this doesn’t really matter.

Written by Sue Shields, mother of Nathan Bessell (who has Down’s Syndrome himself), it’s a simple and semi-autobiographical story, told largely through Odette’s narrative. It skilfully dots back and forth between the present matter of packing the suitcase, the general situation of Matty’s inability to engage with the task in hand, her worry about his future and how he will respond to college, and the past story of their family life from her wedding day to the present. Shields draws pleasing symmetries between Matty’s imminent immersion in college and certain moments in Odette’s life when she has been in a new and daunting situation – her honeymoon, the family’s move from an English city to rural Wales with four young children, or the day after Matty was born and she was called into the doctor’s office to receive the ‘very bad news’.

Bessell has a wonderful physicality, and with choreography from Michelle Gaskell, moments of dance complement his character and add to the narrative, his dreaming, his getting in his mother’s way, his playfulness. I could watch far more of Matty’s dancing but am content to savour the few high quality moments we are treated to. A further dimension is added to Matty’s character by a series of fun, simple animations projected onto a screen at the back of the room. They represent his imagination; brightly-coloured superheroes and jungle animals are conjured in Matty’s mind from a chance word by Odette, blossoming into full-blown adventures where he is the protagonist, leaving his mother’s quotidian anecdotes far behind. They are also a way for him to make sense of the world – we see each of his four siblings morph into a farm animal when Odette describes their characteristics, and when the pair remember a ‘bad man’ who had behaved aggressively towards Matty in the supermarket, we see ‘Supermum’ on the screen, who boots that bad man out of the picture and rescues Matty.

This is a moving and joyful show that leaves you feeling warmth, respect and admiration for both characters. Their frustration with each other, their deep love for each other, and the strong attachment to each other that is on the brink of being broken as Matty leaves, are tangible and affecting. Bristol-born Myrtle Theatre Company first produced this show in 2009 and are touring it again this autumn in association with Salisbury Playhouse. Do go and see it.