Brian Ferneyhough describes Shadowtime, his vast music theatre piece based on the life, death and works of Walter Benjamin, as "an opera of thoughts". Setting an allusive, wordy text by American poet Charles Bernstein, it's a dense work, characterised by a sense of intellectual elitism that makes it inherently forbidding.

Its complexity reflects its subject matter. Benjamin, the great Jewish-Marxist intellectual of interwar Germany, committed suicide in the Spanish Pyrenees in 1940, on discovering that an invalid transit visa would mean deportation to Nazi occupied France. Ferneyhough takes his suicide as the starting point for a seven-scene meditation on his work. There's no linear narrative, and Ferneyhough links Benjamin's existential quest for meaning with an interrogation of musical and operatic form.

The score is rooted in postwar serialism. The use of self-contained musical forms within an operatic span, links back to the work of Alban Berg. The second scene is a guitar concerto, the fourth a formidable piano solo, during which the player has to recite chunks of Bernstein's text. Much of it is up itself, some of it is beautiful, particularly the closing scenes, in which an extended choral threnody winds its way over bell-like electronics. Some have argued that the opera essentially misrepresents Benjamin's work; Ferneyhough and Bernstein certainly emphasise his guarded fascination with mysticism at the expense of his Marxism.

Shadowtime has already been staged in Munich and Paris, though a single concert performance sufficed for the UK premiere. Jurjen Hempel's conducting was clear, if a bit reverential. Ferneyhough's instrumental and choral textures, at once filigree and rasping, were finely explored by Amsterdam's Nieuw Ensemble and the Stuttgart-based Neue Vocalsoloisten. Nicholas Hodges was breathtaking in his piano solo. The reaction was mixed: many walked out, others slept through it. Those who made it to the end applauded respectfully rather than enthusiastically.