Slaves of the Mastery is the second book in the Wind On Fire trilogy by William Nicholson. It picks up the story of twins Kestrel and Bowman five years on from the closing chapter of The Wind Singer. It was first published in 2001. Plot summary At the beginning of the book, the city of Aramanth is greatly changed since events in The Wind Singer. The walls have been torn down, and the poorer districts abandoned. No longer is it run by the strict system of exams; in fact, everyone is pleasant and docile. The change occurred because the city had been released from the grip of an evil force known as the Morah. This new freedom, however, has also severely weakened the city. News of this reaches as far as a distant country known as the Mastery. The country sends an army of a thousand, commanded by young Marius Semeon Ortiz, to destroy the city and take its entire population as slaves. They do so, killing many of the city's residents, enslaving yet more, and leaving no survivors, except for Kestrel Hath. She vows to have revenge on the unknown Mastery, and on Ortiz himself, and begins to follow the trail led by the returning army. The Manth people are brought to the Mastery, a beautiful country built up entirely on slave labor. They are branded and given jobs. Though some of the people begin to actually enjoy work, as they discover that every single person in the Mastery is a slave (except for the Master, ruler of the land, himself). Hanno Hath, father of Kestrel, signs up to be a librarian, while his son Bowman decides to become a night watchman, in order to listen for his approaching sister. Kestrel, meanwhile, faints with exhaustion on her journey. She is rescued by the beautiful Sirharasi (Sisi), Johdila of Gang. As one of the few people who has seen Sisi unveiled, Kestrel becomes her servant and mutual friend. She discovers that Sisi is also travelling to the Mastery to marry Ortiz, the man who led the attack on Aramanth. Kestrel decides to try to use the considerable might of Gang's army, the Johjan Guards, to overthrow the Mastery, and she convinces Zohon, the Guards' conceited leader, that Sisi loves him, and that she will give him a sign to show this. While on a night watch, Bowman is approached by