One of the easiest horror subgenres to get behind is the trapped-in-a-bad-place movie. Who among us hasn’t watched Frozen (no, not that one) or 127 Hours and not wondered what we might do, stuck in the same predicament? It’s a formula so effective that it works even if you’d no intention of setting foot on a ski lift or cycling down a perilous canyon in the first place.

Porta-potties though, we’ve all used one of those. Be it on a building site, music festival or convention area, we’ve all been caught short and forced to utilize the dreaded porta-loo. I myself haven’t used one since the Reading Festival (pronounced ‘Redding,’ nothing to do with books) of 2011, when I nipped in for a wee and had to spend the rest of the day with clothes reeking of second-hand shit fumes. And that was less than thirty seconds’ exposure – imagine being stuck in one.

Such fears inform Lukas Rinker’s Ach du Scheisse! – or Holy Shit! – a film which takes the core conceit of Buried and imagines, this, but in a porta-john instead. Waking up, pinned down in a collapsed porta-crapper, architect Frank Lamm (Thomas Niehaus) must figure out how he came to be there and how he might escape. With the porta-pooper upended in a soon-to-be-exploded construction site, Frank is rapidly running out of time.

Like the best trapped-in-a-bad-place movies before it, Holy Shit! employs a small cast and single location, never once leaving the confines of Frank’s porta-shitter. From there, Rinker spins a whole conspiracy, taking in fantasy toilet lap dances, musical toilet numbers and erotic toilet fantasies. Playing out in real time, ninety minutes of portable toilet is a lot (just imagine how Frank feels) but there’s never a dull moment. As Frank struggles to figure a way out of his turd-filled coffin, Rinker flings humiliation after humiliation at the poor guy, like a Saw movie with a scat fetish.

Still, if you spend long enough in even the most putrid of porta-ploppers, you’ll become numbed to the odours eventually. And so the scatological laughs of Holy Shit! wear thin also, as the absurdities pile up and the gags grow broader. Niehaus’s Frank Lamm is a great leading man, but supporting characters are thinly sketched to the point of caricature. The trapped-in-a-bad-place movie often struggles to resolve itself cleanly, without betraying the purity of the concept (moving from the Single Location setting), and Holy Shit! throws everything it has, to see what sticks. 

What does stick, ultimately, is Niehaus’s frantic performance, and the obscene levels of abuse levelled at him. You don’t come to a film about a man being stuck in a porta-bog without expecting to see a lot of poop, and Rinker more than delivers on this front. It’s also likely to be the best-looking film you’ll ever see set inside a porta-khazi, doing for portable bathroom units what Danny Boyle did for inescapable canyons in the middle of the desert.

A testament to the versatility of the turd, there are many, many, instances of the word ‘scheisse’ in Rinker’s script. The shit of Holy Shit! is literal (human faeces), an insult (little shit!), a cry of frustration (shit!) and, in the most apt case, a cry of disbelief. Holy shit.