The Stranger Don Matteo has just moved into his new parish when the widow of a young Serb involves him in a strange suicide case. Don Matteo visits the factory where the man used to work, searching for clues. Influenced by Don Matteo, the police decide to reopen the case, now investigating the death as a homicide and not as suicide. One of the Serb's colleagues is arrested on homicide charges, but the priest is convinced that he is not guilty and does everything in his power to prove the man's innocence and to discover the truth.