Insecure American graduate student Crispin Leads has come to the Vatican to study burial rituals and catch up with her oldest friend, Sister Lew, historian for the Shroud of Turin. Within hours of Crispin's arrival she witnesses a murder and is drawn into an investigation of multiple homicides. When Lew disappears, Crispin is accused of being involved. Although she doesn't trust him, Crispin accepts the help of a young priest, Roberto Rossini. The pair stay one step ahead of the police and a determined assassin as they try to unravel the mystery.