Värttinä's three female singers began this entertaining yet curious set by walking through the hall, performing Finnish traditional material, unaccompanied and without microphones; they ended by leaping around the stage, pretending to punish the male members of the band for bad behaviour by whipping them with ropes. They then demonstrated their vocal skills with their slickest, most rapid-fire demonstration of harmony work of the night. Folk and acoustic folk-rock were dressed up with pop theatrics.

This was the opening night of the Finnish Line festival, and the band hailed as "Finland's ethnic music flagship" were celebrating their 30th anniversary. Mari Kaasinen, the one surviving singer from the original lineup, was joined by Susan Aho, her colleague for the past 17 years, and newcomer Karoliina Kantelinen, who has daringly broken with Värttinä tradition by not being blonde. For the first set, they wore traditional outfits with long red skirts, and mixed folk songs with their own material inspired by the songs of eastern Finland. Backed by an inventive, attacking band that included violin, accordion, guitar, bass and drums, they switched between ballads, which had the melodic power of great Celtic songs, and bursts of elaborate stagecraft. For their song about washerwomen, they asked for shirts to be passed up from the audience. They were.

For the second set, they reappeared looking equally colourful but more contemporary, and the emphasis was now on folk-pop. There was a reminder that they wrote the music for the stage version of Lord of the Rings, and on Äijö they acted like well-choreographed, demented witches, prowling around the stage, singing about a crazy old man bitten by a snake. They were impressive musicians and didn't need the tacky theatrics – but the technique has brought Finnish folk to a global audience.

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