Edinburgh debuts from experienced comics should always be a dead cert surefire hit. But often those coming from other comedic backgrounds can be left floundering in front of a Fringe audience, unsure of their material and how to unfurl it before a new crowd. Word even has it that US stand-ups Marc Maron and Kirk Fox thought that the Edinburgh Festival was summed up by the Tattoo.

Kirk Fox clearly has a way with the stand-up form. His natural height and width of reference dominates the stage, but his clear disappointment at the lack of hysteria for his off-kilter gags does little to inspire the desired effect in the gathering. Marc Maron, conversely, appears to care less about the reaction to his set and this inherent confidence serves him well. His material about terrorism is pertinent and funny but it's when he delves into the dark recesses of his relationships with women and his parents, that his half of the show truly flies. (Brian Donaldson)

Gilded Balloon Teviot, 668 1633, until 27 Aug, 9.10pm, £9–£10 (£8–£9).