The Red Fox Clan (Ranger's Apprentice: The Royal Ranger #2) by John Flanagan
Picking up where The Royal Ranger: A New Beginning left off, this next installment continues the story arc featuring young apprentice, Maddie, and the student-turned-master, Will Treaty. The time has come for the next generation to assume the mantle and become protectors of the kingdom of Araluen.
After passing her third-year assessment as a ranger's apprentice, Maddie is called home to Castle Araluen. Forced to keep her ranger training a secret, Maddie feels trapped by the monotony of castle life and longs to find a way out. But there are whisperings of a new threat to the kingdom. The mysterious Red Fox Clan, a group of anarchists all donning fox masks, have threatened Castle Araluen and question Princess Cassandra and Madelyn's succession to the throne. Will they succeed in unseating Cassandra and Madelyn and take the throne for themselves?-Goodreads