At first sight the New York-based composer Nico Muhly might seem an unlikely focus for a concert in Scotland Unwrapped, the latest themed series at Kings Place. But in this appearance with the Aurora Orchestra and two folk singers, the Scottish Robyn Stapleton and the Vermont-born Sam Amidon, the focus was very much on Muhly as arranger, in an exploration of a range of ballads and songs from both Scotland and the US. Muhly has long been fascinated by the way in which traditional songs travel across continent, and how they mutate en route, and in particular by the different variants of the murder ballad The Two Sisters, which may have originated in Britain in the 17th century, but exists in more than 500 forms across Europe and the US.

Here three versions of this grisly tale of sororicide were threaded through the programme, two of them in Muhly’s tactful arrangements for the Aurora lineup, the third as the kernel of one of his most striking concert works, The Only Tune, which he composed for Amidon in 2007. The original song emerges word by word through a welter of menacing orchestral textures and sampled sounds, before being deconstructed again, and then eventually is heard in more or less intact forms, sung by Amidon with banjo or guitar. It’s a powerfully effective work that wears well.

With Muhly himself sometimes conducting, sometimes contributing to his arrangements on piano or celesta, the other songs in the programme were much more straightforward. Stapleton’s group of Scottish songs, including the fratricidal Two Brothers, and versions of Robert Burns’s A Red, Red Rose and Robert Tannahill’s Gloomy Winter’s Noo Awa’ were beautifully delivered; the settings Muhly supplied for them were always immensely respectful, and at pains to preserve the integrity of the original, as were Amidon and Muhly’s arrangements of a Texas tale of fratricide, How Come That Blood, and Saro, a song that is thought to have started life in Scotland or Ireland in the 17th century but migrated to the Appalachians.

Short pieces by James MacMillan (his vaguely folksy wind quintet Untold), Anna Meredith (Blackfriars, for amplified string quartet) and Muhly himself (the fidgety Motion for clarinet, quartet and piano, based on a verse anthem by Orlando Gibbons) punctuated the vocal sequence; all were beautifully played by Aurora, but it was always going to be memories of the performances by Stapleton and Amidon, ending with Muhly’s arrangement of Paul Simon’s Hearts and Bones, that one took away from the concert.