Tris's Book (Circle of Magic #2)

In Book 2 of the Circle of Magic Quartet, earthquake damage has left Winding Circle vulnerable to pirate attack and Tris, Briar, Daja, and Sandry are working with the community to strengthen their defenses. When the pirate onslaught begins, two things become terribly clear: The pirates have a powerful new weapon - and they have an accomplice within Winding Circle. But they've failed to anticipate the fury of a young mage who has been betrayed once too often, and who has very stubborn, very loyal friends . . .