Josh Howie's new show, Aids: A Survivor's Story, has a captivating conceit. It relates Howie's experience growing up against the backdrop of the 1980s Aids epidemic. It's almost a satire on comedy shows about illness or bereavement, and Howie almost persuades us that he contracted the HIV virus. The almost is emblematic: Howie's diffident demeanour is the opposite of wholesale commitment. The show doesn't honour its potential, or the quality of some of its jokes, because Howie doesn't sell it with sufficient confidence.
This is frustrating, because the show is creatively ambitious (its tightrope walk between truth and misdirection is both playful and, given the subject matter, risqué) and packed with well-written gags. Howie starts with a blast of Frankie Goes to Hollywood, evoking a "Don't Die of Ignorance" era of Aids deaths and sexual panic, which happened to coincide with his own neurotic adolescence. "Condoms were my generation's underground nuclear bunkers," he tells us, as he narrates the story of his teenage fling with his sister's flatmate. Young Howie is persuaded to try unprotected sex – and the rest is hysteria.
At its best, the show evokes its era – and Howie's nebbish personan – vividly. And there are some zingers, like his pretend misunderstanding of Roman Catholicism's opposition to contraception. But even the funniest lines are apt to be thrown away: Howie often dispatches them in passing, barely giving them the status of jokes. And there's poor material here, too, like the suggestion that Forrest Gump is an Aids movie – which is adequately argued, but not remotely amusing. What's vexing is Howie's refusal to promote his own material. It's as if by not trying to get laughs, he won't get hurt when laughs aren't forthcoming. Maybe so – but it's an approach, and a delivery, that leaves this potentially strong show damagingly undersold.
• Until 23 August. Free and non-ticketed. Details: 0131-226 0000. Venue: Canons' Gait, Edinburgh.
