Not many acts would open a show by hurtling around the stage to the tumult of deathcore stalwarts Suicide Silence, but Patti Harrison is a performer plowing her own furrow through the industry. It’s likely that her increasingly prominent work in TV and film, such as Shrill, The Lost City, and I Think You Should Leave – where she often manages to out-gonzo the reliably gonzo Tim Robinson – will lead to an eventual withdrawal from stand-up. A packed room at the spacious Pleasance Forth suggests people are taking a likely rare opportunity while they can.

The versatile Harrison breezes leisurely through a show that demands to have its cake and eat it. Gentle introspection, jet black outrage, stunningly convincing songs in the style of Joanna Newsom, Björk, and Kate Bush; it’s all there, with Harrison barely bothering with anything as normal as a structure. She gives a reason for this freewheeling nature, but as usual, how much we can take at face value is debatable.

Her claim that this is a work-in-progress and her stand-up muscle memory is a little atrophied is a wee bit disingenuous given she’s been performing a variant of this show for around a year. Still, it encapsulates Harrison’s occasionally sweet and sour concoction of ingenue sincerity and fire hose jets of irony. The difficulty lies in working out which she’s employing at any given moment.

She certainly enjoys baiting the sensibilities of her audience. Her earnest delivery of increasingly absurd trigger warnings are immediately undermined by inappropriate parps, farts, and clangs from the stock sound effect ‘sponsors’ of the show. Later, her description of an encounter with a ‘glowing’ pregnant woman ends with some gleefully hideous imagery that would shock a grizzled Jerry Sadowitz audience.

Yet, it’s all consistently so disjointed; some remarkable highs with some undeniable lulls as she drops her voice to a whisper and seems to be speaking almost to herself, as if testing whether she can keep a crowd’s attention solely through the force of her own magnetism. Largely she can, even as her set meanders with all the lackadaisical inertia of a Fringe crowd on North Bridge.

Seeing Patti Harrison definitely feels like one of those ‘I was there’ moments, witnessing somebody just about to go stratospheric. However, there’s an unfocused nature to her approach that also makes it a slightly frustrating experience. Sporadic brilliance is still brilliance, but this is a show that could do with some tightening.