Penance by R. Craig Henderson

A stray rifle bullet brings Lieutenant Colonel Paul Richter's military career to an ignoble end. A man without a future, Richter is approached by an old friend from his military past with an offer to teach high school in a small town in rural South Georgia. Richter soon learns that educating sullen American teenagers is not his biggest challenge, as he finds himself at odds with the local crime boss and a shadowy priest who has big plans for this small community. As Richter gets drawn in to confronting them and resurrecting skills he thought he no longer needed, he begins to wonder if there was more to this offer than just a teaching job. He has finally found work that he enjoys, a place to call home, and the love of an extraordinary woman. Now, if only criminals and terrorists were not trying to kill him...