Much has been written about Cristian Ceresoli’s startlingly raw cry of the heart La Merda. First and foremost, it is a breath-taking slab of physical theatre, and Silvia Gallerano’s extraordinary central performance provides what must be the last word in confrontational art.

After a decade of touring globally it seems fitting that this 10th anniversary showing should take place in the forensic surroundings of Summerhall’s Demonstration Room, given the often-animalistic nature of what is presented.

Perched atop a high black stool, the exposed and starkly lit Gallerano opens in her skittish, wavering voice, to recount her life and experiences to the audience, violently contorting into each character, mimicking their voices in grotesque, mocking derision. The astonishing physicality needed to invoke the dark spectre of her abusive father and her disabled classmate is both shocking and wonderous as each increasingly disturbing tale unfolds.

Juxtaposing such a precarious and contained performance space with Gallerano’s ferocious eruption into the embodiment of female primal rage is something that seems impossible but proves to be the essential heart that gives this story such visceral power.

Distorting herself to desperately fit into the ever-narrowing image of what constitutes ‘celebrity’, each encounter of abuse, pain and fear feeds her brutal, searing fury in a devastating stream of consciousness that assaults the senses.

Wholly appropriate too is the title – The Shit – with the story a metaphor for the unbroken cycle of digestion, excretion, and reabsorption of everything from the rise of fascism to male abuse of power and societal obsession with female body image. The concept equivalent of a snake eating its own tail.

‘You need to have courage, because the train doesn’t always stop at your station’, says Gallerano. If you have the constitution to experience this visceral, gut-punch of a performance, that courage will be richly rewarded.