Born in Los Angeles in 1976 of Zimbabwean and Japanese descent, Nokuthula Ngwenyama first came to prominence as a talented viola player, but her career has branched out more recently into composition. Unsurprisingly, a large portion of Ngwenyama’s output has been for string instruments, and it therefore seems fitting that her most significant work to date – the 21-minute Flow – is written for string quartet.

Critics have often drawn attention to the direct and immediate qualities belonging to Ngwenyama’s music, evidence of which can be found in the finale of Flow (subtitled ‘Enjoy and go with the flow’), which ends jubilantly on a striking D major chord. Nevertheless, up to that moment the musical direction of the piece is anything but clear. Drawing inspiration from a range of spiritual and scientific concepts and ideas, Flow begins atmospherically with trembling tremolandos and glassy glissandos alongside a halo of harmonic overtones. This sense of uncertainty and unease is also captured in the second part of the Prelude, with its spiralling whole-tone lines, and later during the middle section of the Lento second movement, which features an eerie-sounding ‘wrong-note’ melody. Such moments of dramatic tension are offset by assertive tonal and lyrical passages, which during the third-movement Scherzo give rise to a pastiche 19th-century Viennese waltz. A brief return to the unsettling mood of the opening movement finally gives way to a powerful and radiant ending.

The range of references is much wider than in other pieces I’ve heard by Ngwenyama – testament to her ability to harness these multiple stylistic strands to convincing creative ends. The Takács Quartet, for whom Flow was written, offer an energetic and engaging account of the work, aided by solo cameo roles for viola player Richard O’Neill and cellist András Fejér, and assisted in no small measure by Ngwenyama’s own personal understanding of the medium itself. Worth exploring.