Old St Paul's is a historical novel that describes the events of the Great Plague of London and the Great Fire of London. The story spreads between April 1665 and September 1666 and details the events of the grocer Stephen Bloundel's life. His daughter Amabel is wooed by Leonard Holt, the grocer's apprentice, while she in turn pursues Maurice Wyvil. This happens while a plague hits London, and St Paul's Cathedral is turned into a place to house the sick. During the plague, London is filled with plague victims while many people go around killing and robbing the sick. Bloundel seals his house to avoid the plague. Holt wanders alone in London and catches the plague, and Amabel goes away to marry Wyvil. However, Wyvil, really John Wilmot, the Earl of Rochester, holds a fake marriage, and when Amabel finds out she grows sick and soon dies. Eventually, Holt recovers from the plague and continues to wander London, meeting Nizza Macascree, a woman who is soon revealed to be Lady Isabella Argentine. As they grow fond, the London fires are started by a group of religious zealots, and London is in danger again.