In August 1100, King William II died while hunting in the New Forest, apparently hit by a stray arrow. Whether he had ordered the king’s death or not, William’s younger brother Henry was ready. Leaving the dead king’s body, he disregarded the claims to the English crown of his older brother, Robert, raced to Winchester to capture the royal treasure, was crowned at Westminster three days later and swiftly married Edith (also known as Matilda) of Scotland, a descendant of Anglo-Saxon royalty, to complete his power grab.

Four short months after his brother’s death, Henry I held his first Christmas court at Westminster. Among the guests was his second cousin Louis, eldest son of King Philip I of France and heir to the throne. Louis’s father had already crowned him and designated him his successor. But the festivities were interrupted by the machinations of Louis’s stepmother, who, wanting one of her own sons to succeed, forged a note from Louis’s father demanding that Henry imprison Louis for life.

This is where Catherine Hanley opens her book, which tells the story of the Plantagenets (and their Norman predecessors) and the Capetians, two separate but intimately connected families who presided over the forging of the kingdoms of England and France. Exhibiting little familial feeling and containing many repulsive