Second Book of the Change.
The second book in the trilogy opens with Sal and Shilly heading for the Interior, fleeing the Alcaide and the Syndic and following the only clue they have: the name of Lodo's old teacher, Skender Van Haasteren. As hinted in Sal's dream, they are followed by Tom's brother, Tait, and his senior Sky Warden, Shom Behenna, the new Selector for the Fundelry region. Sal knows they are being pursued. He and Shilly have no choice but to use their incomplete training in the Change in order to survive.
The tension between Behenna and Sal is a central dynamic of the book with Behenna (the Sky Warden of the title) regarding Sal as his means of rising rapidly through the ranks, and Sal seeing Behenna as a symbol of everything from which he and Shilly are fleeing.
It slowly becomes apparent that Sal is the focus of a bitter tug-of-war between several rival factions of a secretive group called the Weavers, and Sal's relationship with Shilly is also tested as he is unsure of what he feels for her.
