History books tell us Flora Macdonald is a Jacobite heroine, the woman who smuggled Bonnie Prince Charlie over the sea to Skye. But as Flora – the Flora of this story – informs us, “facts are overrated”. And so we gather to gasp and giggle at an even more legendary tale: where a cat (yes, a cat) travels the whole length of Europe, nominates Flora the Ultimate Embodiment Of All Human Goodness, and thus kick-starts her conversion to a zombie slayer. Obviously.

This is all the invention of Edinburgh-based writer and actor Debbie Cannon, whose style sits on the cusp of storytelling and solo theatre. Her tale may be set in a comic-book world, but Cannon’s gift for detail draws us into the reality: to the storm-wracked shore of Skye, to a zombie-beleaguered cottage, to the National Trust gift shop at Culloden. Along the way she narrates the action through a handful of characters, each of them magnificently realised and perfectly defined.

The narrators play to comfortingly familiar tropes: Flora’s the sweet highland lassie, Prince Charlie is dashing but dim, the modern-day schoolgirl gets things a tiny bit wrong and the cat bears more than a passing resemblance to the one out of Shrek. Most interesting, though, is the king of the zombies, whom Cannon portrays as a cross between a YouTube-famous entrepreneur and a Prohibition-era mob boss. With an eerily convincing sales pitch to deliver, he’s a genuinely frightening creation – and not just because he mentions his flesh is falling off.

It’s hard to say exactly what makes this all so funny. Perhaps it’s the way it frames treasured national myths in the storytelling equivalent of a carnival mirror. Perhaps it’s the nonchalant insertion of twenty-first century superfans into a Jacobite-era tale. Perhaps it’s Flora’s studied sweet good nature, even as she hacks off zombie heads with her particularly enormous sword. Or perhaps it’s Cannon’s unwavering commitment to taking the story seriously – never once allowing herself a wink at the audience, no matter how absurd her imagery becomes.

Whatever the reason, it’s the kind of slow-burn humour that progresses from quiet chuckles to delighted giggles, with unconditional surrender to continuous laughter your only option by the end. There’s a touch of the bittersweet to counteract the innocence, and you could argue there’s a feminist narrative somewhere amidst the zombie-slaying, but ultimately this is just a very silly story told in an utterly convincing way. Do be warned: there are cartoonish but vivid descriptions of viscera, and you may leave with a Feargal Sharkey song stuck in your head. But the the legend that is Flora would laugh at such dangers. And surely, so will you.