The Boxer and the Spy by Robert B. Parker
When a shy high school student’s body is found washed up on the shore of a quiet beach town – an apparent suicide – Terry Novak doesn’t know what to think. He decides to do some investigating with the help of his best friend, Abby. Before long, they learn that asking questions puts them in grave danger. Fortunately, Terry has been learning about fighting, thanks to a retired boxer, who teaches him to use his head and keep his feet set beneath him – lessons Terry takes to heart in more ways than one. Robert B. Parker delivers a taut, empowering mystery for teen readers.