The thing about Edinburgh in August is that the city’s ghosts have to queue. They’re suddenly outnumbered, you see, jostling for space between a silent mime from Kyoto, a twenty-person acapella group from Yale wearing sponsored lanyards, and a man juggling flaming pineapples. The whole place becomes a glorious, pop-up psychic bruise. I was mainlining this year’s particular vintage of glorious chaos when I stumbled past the Preston Street Primary School. It’s a perfectly normal school playground. Brightly painted walls, a climbing frame, the faint, lingering scent of disinfectant and existential dread. Except this particular patch of publicly-funded joy is built on a historical feedback loop of profound unpleasantness. It’s a place that gives you a profound system error in the soul; a patch of reality where the source code of the past has started bleeding through the brightly coloured, EU-regulated safety surfacing of the present. It’s the kind of psychic stain that makes you think, not of a hamster exploding, but of the day the children’s laughter started to sound digitally corrupted, looping with the faint, static-laced echo of a hangman’s final prayer. It’s the chilling feeling that if you looked too closely at the kids’ innocent crayon drawings of their families, you’d notice they had instinctively, unconsciously, drawn one of the stick figures hanging from a tree.

So naturally, in my Fringe-addled brain, I pictured the school’s inevitable entry into the festival programme. It’s the hit no one saw coming: “Our Playground of Perpetual Shame: A Musical!”, brought to you by the kids of P4. The opening number is a banger, all about the 1586 construction of the gibbet, with a perky chorus about building the walls high “so the doggos can’t steal the bodies!” It’s got that dark, primary-colour simplicity that really resonates with the critics. The centrepiece is a complex, heavily choreographed piece depicting the forty-three members of Clan Macgregor being hanged for their murderous beef with the Colquhouns. Mr. Dumbeldor from P.E. has them doing it with skipping ropes. It’s avant-garde, it’s visceral, it’s a logistical nightmare for the school trip permission slips.

The second act, of course, delves into the ethnic cleansing of the Romani people under James VI. It’s a tough subject, but the kids handle it with a chillingly naive sincerity. They re-enact the 1624 arrest of their “captain,” John Faa, and the great rescue attempt. Little Gavin Trotter, played by the smallest kid in P1, is “cunningly conveyed away” from a prison of gym mats while the audience (mostly horrified parents) is encouraged to create a distracting “shouting and crying.” It’s the most authentic immersive theatre experience on the circuit. They even have a whole number for General Montrose, whose torso was buried right under what is now the sandbox. His niece, played by a girl with a glittery pink art box, comes to retrieve his heart. It’s a tender, if anatomically questionable, moment.

Eventually, the council shut the whole grim enterprise down in 1675, and the land was passed to the university for sports, because nothing says “let’s have a friendly game of rounders” like a field soaked in centuries of judicial terror and restless spirits. Now, kids play there. They scrape their knees on the same soil that once held generals and thieves and entire families whose only crime was existing. And you watch them, in their little hi-vis jackets, and you have to wonder. Maybe this Fringe show isn’t an act. Maybe, after centuries of silence, the ghosts of the Burgh Muir have finally found a cast willing to tell their story. And judging by the queues, they’re heading for a five-star review.