Crystal Mask is a fantasy novel by English writer Katherine Roberts. It is the second novel in The Echorium Sequence, and it is the sequel to Song Quest. The novel was first published in 2001 by the Chicken House. is set in the world of the Isle of Echoes where the Singers live in The Echorium. The Singers have many special abilities, the most important of which is knowledge of the Songs of Power: Challa for sleep, Kashe for laughter, Shi for sadness, Aushan for fear and Yehn for death. All Singer children, called novices, learn these Songs, but if their voices do not last into adulthood they receive a mild form of Yehn which makes them forget the Songs. The Singers can also farlisten to hear over great distances, an ability enhanced by the bluestone which the Isle is made up of, and hear truth. The Singers help to keep peace on the mainland, and produce treaties to protect Half Creatures – the half-human beings with knowledge of the Songs, which include merlee (fish people), naga (water snake people) and quetzal (bird people). During the novel Song Quest, set twenty years before Crystal Mask, the Singers encountered a powerful enemy in Khizpriest Frazhin, who harnessed the powers of a strange black crystal called the khiz to manipulate people's thoughts and memories. He attempted to destroy the Echorium by kidnapping a novice, Rialle, and was only stopped by the efforts of another novice, Kherron, who had originally been taken in by Frazhin. Although Frazhin was apparently killed by quetzal after the Battle of the Merlee at the end of Song Quest, and finished off by being sung Yehn over a distance, his body was never recovered. While the khiz was thought to be destroyed, the arrival of a girl for treatment with memories of a khiz crystal mask which steals thoughts leads the Echorium to believe that Frazhin may have survived. Source: Wikipedia (en)