Ranger's Apprentice: Death of a Hero by John Flanagan

I won't say much about this very short book, but it will give readers a feel for the other books in the series. This book tells the story of Will's parents and how Halt came to know them. In book one, The Ruins of Gorlan, Halt kept this information secret, and he never told Will the truth, until now. Will's father died heroically saving Halt's life in a great battle, and Will's mother died saving him too. Halt felt their deaths were his fault and thought the truth would make Will bitter and angry. It's an enjoyable story that can be read on its own.