The Courage Consort, possibly the seventh best-known a cappella vocal ensemble in Britain, are given two weeks in a Belgian chateau to rehearse their latest commission, the monstrously complicated Partitum Mutante. But can the piece be performed? Does it matter that its composer is a maniac best known for attacking his wife with a stiletto shoe at the baggage reclaim of Milan airport? Can the five members of the Consort endure their own sexual tensions and wildly differing temperaments? And what is the inhuman voice that calls out to them from the woods at night? The esoteric world of avant-garde classical music is the unlikely setting for a story of rare power - perhaps the most moving Michel Faber has yet written.