15th century England, and the War of the Roses has ended in a Yorkist victory. With some hopes of normalcy in the offing, the cathedral town of Canterbury is going about its business of attracting and profiting from pilgrims. Until someone begins poisoning them. Kathryn Swingbrook, an apothecary who may or may not be a widow, teams up with Yorkist soldier Colum Murtagh to solve the murders.