You can appreciate why Harri Ahmas describes his 2008 work Käärmesormus (‘Snake Ring’) as a ‘chamber opera’ but the title is far from ideal. Pinning down this piece for mezzo and ensemble isn’t easy, but it sits somewhere between Schubert’s Winterreise (in its setting of first-person poems that link to form a narrative), George Benjamin’s Written on Skin (in the mystery of its 16th-century French setting) and Turnage’s Twice Through the Heart (a woman dealt a cruel hand indulging in a series of confessional monologues). Turnage describes his work as a ‘dramatic scena’ and that seems a better term for this piece too.

Tittamari Marttinen’s poems on the subject of a Burgundy woman forced to renounce her true love and marry a stranger also carry something of Written on Skin’s eroticism, if not the tension that piece creates between characters, as here the protagonist Beata Lyonnaise sings/speaks alone while the ensemble recites her epilogue. Ahmas sets each of the poems as a single entity with its own gait and stylistic colouring. Sometimes the music has a pained, atonal lyricism. Sometimes it pastiches klezmer and other clear styles. Sometimes it devolves into etched neoclassicism.

It can be hard to locate the discourse and its various stylistic adventures. But while Ahmas’s music can sprawl conceptually, it is filled with invention, compositional discipline, extraordinary instrumentation (never do you tire of the 16 hands of the Zagros Ensemble) and a deep yet instant reaction to the text that gives it an almost Italian feel. When it matters, Ahmas controls himself with good use of ostinato and patterning – or the pure colour of an instrument – even if he can sometimes appear to be too inventive for his own good.

Mezzo Ulla Raiskio herself discovered Marttinen’s poems so we have her to thank for the existence of the piece. She sings with all the passion (both railing and veiled) that the woman’s descent demands. But her voice is heavy and never sounds intimate or fragile, which is a key tenet of the narrative. Whatever Käärmesormus is, it’s some achievement. Multiple further listens might reveal whether it’s a strange masterpiece or just plain strange.