Medieval physician Kathryn Swinbrooke is summoned to investigate the disappearance of a sacred relic, the Lacrima Christi, from a well-guarded chapel in Canterbury. Shortly after the relic vanishes, its owner, wealthy lord Sir Walter Maltravers - a former soldier with a troubled past- is found savagely murdered in the maze of hedges in his own garden. As a killer, clearly bent on revenge, continues to strike and more bodies turn up, Kathryn is drawn into Maltravers's shadowy history in her search for answers.