There's no such thing as a free show on the Free Fringe.

You don't pay to get in but you're expected to drop something into the hat/basket/bucket on the way out, and you'd have to be a proper Scrooge, or flat broke, not to contribute to Paul Dabek's bar tab – at least.

Dabek is a professional performer with a very professional show, although the gags he makes as freely against himself as his clientele sometimes claim otherwise. He has particularly plentiful supply of lines, many of them in mirthful, fluent navvy, to let his audience know how slow they are to applaud his sleights of hand – but the truth is, the tricks happen so fast that it can be hard to keep up.

Among the disappearing handkerchiefs and mind-bogglingly changeable lengths and loops of rope, one audience victim picks a number and wins a hug – the five alternatives all entail a deeper relationship – and another victim donates a £20 note only to discover that, while Dabek may indeed have nothing up his sleeve, he has something very clever going on inside a loaf of bread. To save you wondering, the £20 is refunded but I won't spoil the "bonus track" that you'll miss if you try to dodge Dabek's top hat by sneaking out at the false ending. It's possibly the best bit of a genuinely entertaining show.

Ends August 25

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It's easily seen why Colours of Tango is in the Music section: while the dancing feels a bit uninvolved and perfunctory, the three Polish musicians on violin, accordion and harp play splendidly – beginning with a handful of Astor Piazzolla masterpieces and going back into earlier tango classics – and vocalist Oscar Ernesto Ovejero emerges as the star of the show. Ovejero, who also contributes guitar and empathetic, musical cajon (wooden box) playing, ranges expressively from the confidential to the conversational and on to an impassioned delivery. You don't need to speak Spanish to get the gist of what he's singing about and he makes Piazzolla's Balada Para un Loco come alive with engaging madness.

Ends August 18

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The Wonderful Sisters – Gloria, Ruth and Fanny – welcome us as wartime troops to be entertained and as PG-rated, harmoniously talented successors to the Anderson Sisters, they set about taking our minds off battle with ditties about family life in the Southern States (more than their hearts belong to daddy, it transpires), plans for world domination and- murder. First Winston Churchill succumbs, then Fanny suffers sororicide, thus spoiling the "hits" that were specially written for three. Despite backing tracks that are sometimes funnier than the script, it's a by turns clever, bizarre, and agreeably daft and diverting 50 minutes.

Ends August 25.