Based on the epistolary work by Ugo Foscolo.
When the eyewitness to a brutal murder decides not to testify, the actual murderer chooses to finger him as the murderer and claim eyewitness status for himself.
Don Matteo is a thoroughly ordinary Catholic priest with an extraordinary ability to read people and solve crimes. He’s a parish priest who never met an unjustly accused person he didn’t want to help.