Plainte is the 3rd part of Langlais' Suite Brève, composed in 1947.
For the Plainte, Langlais re-used some orchestral music he had written as accompaniment for a radio broadcasted theatre piece titled "Le diable qui n'est à personne" (the devil who belongs to nobody).
It's a slow meditative piece and its last part is even more "stretched", like is sometimes Messiaen's music.
It was a good opportunity to have a try at Regensburg's flutes, voix céleste and "goats' choir" which, Imho, prove themselves well fitted to this music.