A Vow of Penance - Sister Joan, Bk 5 Author:Veronica Black When the cheery housekeeper at the Convent of the Daughters of Compassion is found dead of a pill overdose, Sister Joan refuses to believe the police verdict of suicide. When someone starts mutilating the convent's trees and then a bloody axe is found in the chapel, the fearless nun decides to set a trap for the killer.