Halt's Peril (Ranger's Apprentice Book 9) - John Flanagan

Will, you will survive this battle, but others may not be so lucky. You are on the trail of an evil gang - the Outsiders, who have escaped justice for their crimes. Halt is determined to stop them but they are sneaky, cunning and dangerous. When the battle begins, will your extraordinary archery skills be enough to save you all, or will this be your mentor's final battle?