On a dark, snowy night in 1363, Nicholas Wilton, Master Apothecary, delivers an herbal remedy to the Infirmary at St. Mary's Abbey. When the medicine proves fatal to the ward of the Lord Chancellor of England, Owen Archer, formerly Captain of Archers, is ordered to York to find out what happened. For his cover, Archer goes to work for Apothecary Wilton as an apprentice, and falls in love with the ambitious Lucie, Wilton's wife. As Archer unravels...