The priest kept a diary of confessions. FBI Special Agent John Treehorn hunts for a killer in a small Upstate New York town who committed a double homicide of a priest and his housekeeper. The agent joins forces with the New York State Police to investigate the crimes that occurred in federal and state jurisdictions. The investigation soon exposes a priest who kept silent about a horrible crime and then wrote the details in his private diary which the killer stole. When it is discovered that the two deaths and a cold case are connected by the murder weapon, the law enforcement officers hunt for the perpetrator as the Church fights to keep the original sin a secret, the State wants the criminal arrested, and Special Agent Treehorn wants justice.