Alex Bernier (Heath Ledger) is a member of an arcane order of priests who is sent to Rome to investigate the mysterious death of the head of this order. The body may be of a Sin Eater, a renegade who offers absolution, last rites and therefore a path to heaven outside the jurisdiction of the church. Alex enlists the aid of his old comrade Father Thomas and of a troubled artist (Shannyn Sossamon) upon whom he once performed an exorcism. He soon finds himself plunged directly into the face of unimaginable evil, murder, and ultimately, a fate worse than death.