Royal ranger. John Flanagan. 2013.

After a senseless tragedy destroys his life, Will is obsessed with punishing those responsible - even if it means leaving the Ranger Corps. His worried friends must find a way to stop him taking such a dark path.

It is Halt who suggests the solution: Will must take an apprentice. The candidate Halt has in mind surprises everyone - and it’s a request Will cannot refuse. 

Training a rebellious, unwilling apprentice is hard enough. But when a routine mission uncovers a shocking web of crime, Will must decide where his priorities lie - finishing his quest for revenge, or saving innocent lives?