Books like A vow of penance by Veronica Black

Dame Frevisse, a nun, leaves her cloister to chase her outlaw cousin Nicholas up the King's Highway, confronting the law, her vows, and a deadly manor where faith and greed collide.

In medieval Prior Byfield, plague and famine grip the village while a twisted web of adultery, crime, and intrigue threatens its inhabitants. Nuns Sister Frevisse and Sister Thomasine investigate the betrayal that endangers the nunnery and the community.

A dark lady rides back into the life of Dame Frevisse, bearing with her two small boys haunted by the touch of death and scandal. Nine men lie dead on the road behind them, victims of the grim fate which relentlessly pursues them. Some seek to turn them away, but when they request sanctuary Frevisse is bound by her holy oaths to grant it. But in welcoming them within the walls of St. Frideswide, has Dame Frevisse allowed death to stalk the nunnery's halls? When she begins to untangle the mystery of these strange guests, the truth she discovers may be enough to doom them all. Forced to keep secrets better left untold even from the nuns of her own order, Frevisse is caught in a crucible between faith and duty. To learn the boy's name is to be drawn into a conspiracy of shame. To hear the boy's tale is to face death. Sister Frevisse - Book 05