Halt's Peril by John Flanagan

In this gripping installment of the Ranger's Apprentice series, the story follows the seasoned Ranger Halt, his apprentice Will, and their friend Horace as they pursue the deadly cult known as the Outsiders. The trio embarks on a perilous journey across the kingdom, facing treacherous terrain and cunning adversaries. As they close in on their quarry, Halt is struck by a mysterious illness, leaving Will and Horace to confront the looming threat alone. With time running out, they must rely on their skills and courage to thwart the Outsiders' sinister plans and save their mentor.

Purchase from Bookshop.org