Alex Bernier (Heath Ledger) is a Catholic priest in a dying order who is obsessed with knowing the mystic, secret truths of the church. When he is called upon to investigate the suicide of his mentor, Dominique, he finds reason to believe that the death was not self-inflicted. Instead, there is evidence that a “Sin Eater” (Benno Furmann) performed an ancient ritual designed to grant absolution to unrepentant sinners apart from the power of God and the church. The Sin Eater accomplishes this feat by taking the burden of a person’s sin upon himself at the moment before death. With a mystery before him, and the forces of church politics and various sinister powers working against them, Alex and his cohorts, Mara (Shannyn Sossamon) and Thomas (Mark Addy), seek out the Sin Eater.