In 2011 pianist Mitsuko Uchida led a suitably moonstruck performance of Schoenberg’s 1912 monodrama Pierrot lunaire at the Salzburg Festival. Actress Barbara Sukowa, whose work with Rainer Werner Fassbinder spearheaded new directions in German cinema during the 1970s, took the Sprechstimme role, as she had already done in 1998 when she recorded the work with Reinbert de Leeuw (Koch). And the ensemble Uchida assembled – Marina Piccinini (flutes), Anthony McGill (clarinets), Mark Steinberg (violin), Clemens Hagen (cello) – punched above its all-star weight in a way that Boulez’s similarly starry 1977 performance (Barenboim, Zukerman et al) singularly failed to do.

From the get-go Matthias Leutzendorff and Christian Meyer’s excellent documentary, built around Uchida’s Salzburg performance, reminds us that it was Igor Stravinsky who labelled Pierrot lunaire ‘the solar plexus of modernism’ and, like The Rite of Spring, Schoenberg’s grasping at a bold new future was rooted in ancient runes and mythology. Sukowa gives us the low-down on Sprechstimme, Schoenberg’s half-spoken, half-sung warble that can feel so alien to Anglo-Saxon ears. In non-amplified turn-of-the-century theatres all vocal utterance tended towards the overcooked and hysterical. And, as Marina Piccinini adds, the piece teleports us back to a world where people were actually prepared to take lavish amounts of time and space and deploy extravagant wordage to express themselves.

The documentary is not immune from statements of the bleedin’ obvious – that the viola is essentially a lower-pitched violin comes as no surprise – but Uchida’s keyboard illustrations prove an essential primer. As she morphs an archetypal Viennese waltz into an atonal reimagining, compositional sources are clarified; as she telescopes inside a key motif, slowing down to repeat its lizarding ugliness, we internalise the ghoulish fear that Schoenberg was trying to communicate.Sukowa’s 1998 recording was blighted by throaty stage laughs and lucky-dip falsettos – a noble misfire. But this new one is clearly the work of someone who has thought about the piece for a long time. Her voice is ethereal, otherworldly, haunted. We feel the air from another planet. Anthony McGill talks up his preference for unconducted Pierrots and the utterly alive in-chatter of the ensemble proves his wisdom.