Edinburgh comedy award-nominated in 2017, Elf Lyons can’t be accused of treading the conventional career path since. None of her shows ever remotely resembles the next. Created with the deaf artist Duffy, Heist is a part-improvised, largely mimed and entirely chaotic comic play about – well, what is it about, exactly? Guinea pigs. Bank robbery. An “evil alien nonce”. I spent a fair portion of the show wondering what and why, until Lyons pipes up with “none of this show makes sense. It’s just made out of my favourite signs from Level One [BSL]!” Aha. That explains the eccentric content. As for the precarious form of a show that doesn’t seem to know whether it’s scripted or improvised – well, that’s all part of the ramshackle fun, as Elf berates Duffy between (and during) scenes about his lax narrative discipline. No point pretending the story is clear, or that it adds up to much more than randomly generated nonsense. But it doesn’t lack jeopardy. With car chases, abseils down tower blocks and severed testicles, Heist might be Elf and Duffy, but it’s definitely not ’elf and safety. Its chief pleasures are to be found in the dynamic between Lyons and her co-star – now quarrelsome, now trusting, and spiced by a running gag about the former’s unrequited love for the latter. There’s also, particularly in the introduction, a cheering irreverence towards deafness and its attendant sensitivities that recalls FlawBored’s disability satire It’s a Motherf**king Pleasure elsewhere on the fringe. Props to Elf and Duffy’s BSL interpreter too, who gamely mucks in with all this. It can’t be easy to keep up with the show’s helter-skelter combination of Lyons’ backchat, the foley sound effects she brrrs and squeaks into her (faulty) microphone, and the frantic visual vernacular storytelling (a mix of BSL, mime and strong gesture). We end up with something resembling a Pajama Men show on speed, with less precision and more jokes about serpentine vaginas. A likable piece of harum-scarum physical-comedy havoc. At Monkey Barrel at the Tron, Edinburgh, until 15 August All our Edinburgh festival reviews