In the winter of 1142, heavy snow brings down part of the guest hall roof at the Benedictine Abbey of Saint Peter and Saint Paul in Shrewsbury, and Brother Haluin falls attempting the repair, taking grave injuries that seem certain to kill him. Believing himself on his deathbed, Haluin confesses to Abbot Radulfus and Brother Cadfael a secret he has carried for eighteen years: as a young man he loved Bertrade de Clary, whose mother forbade the match, and when Bertrade fell pregnant he gave her herbs meant to end it, herbs that killed her instead.
Haluin survives, against all expectation, and asks to make a penitential pilgrimage to Bertrade's grave. Cadfael accompanies him on the journey, but when they reach the church where she was said to be buried, they find no tomb at all. What unfolds is a story of old, hidden loves, hastily arranged marriages, and a fresh act of violence rooted in a truth Haluin never fully knew.