Only months after solving her first mystery, Madeline Mann is called to do God's work--or so says her former English teacher, Sister Moira--by investigating the mysterious death of a young nun named Sister Joanna.
Joanna's death is ten years in the past, but Moira has been troubled by dreams of her young friend, and she is convinced that Joanna was murdered.
Having heard of Madeline's investigative skills, Moira asks her to look into Joanna's death and find out if a murderer still lurks in the town of Webley, and if the dark secrets behind the death of a nun have somehow placed other people in danger.