Most of the series is set in the land of Gwynedd, one of the fictional Eleven Kingdoms (portions of King Kelson's Bride take place in the rival kingdom of Torenth). Gwynedd itself is a medieval kingdom that roughly parallels 10th, 11th, and 12th century England, Scotland, and Wales with a powerful Holy Church (based on the Roman Catholic Church), and a feudal government ruled by a hereditary monarchy. The population of the Eleven Kingdoms includes both humans and Deryni, a race of people with inherent psychic and magical abilities. Throughout the course of the series, relations between humans and Deryni result in ongoing political and religious strife that is often interconnected with the individual lives of the main characters. While the plots of the novels often involve political, ecclesiastical, and military conflicts on a grand scale, they are counterbalanced by details of the characters' personal lives. Neither race is depicted as inherently "good" nor "evil", as both humans and Deryni are depicted as protagonists and antagonists at various points of the series. Additionally, the novels often depict the characters engaging in various forms of magic, and such scenes vary in importance from minor events to significant plot points.
The five Deryni trilogies were published in an order which does not match the internal literary chronology of the series. The first four trilogies alternated between the 12th and 10th centuries, while the fifth trilogy is set immediately prior to the events of the first trilogy. The stand-alone novel, King Kelson's Bride, takes place after the third trilogy. The trilogies are briefly listed by publication date below, with a more detailed listing after.
Set in the year 1089, only 300 copies of this rare, limited-edition short story were published.
Deryni Tales (2002)
A collection of short stories written by fans of the Deryni series. Katherine Kurtz edited the collection and contributed an additional short story of her own. Kurtz' story, "The Green Tower", is set in 1052 and tells the tale of two young girls and the events surrounding a dangerous magical experiment.
Written by Katherine Kurtz and Robert Reginald, this book is a comprehensive encyclopedia of the people and places in the Deryni series, including maps and genealogical charts. The first edition of the book was a limited-edition hardcover slipcase of which only 500 were printed. In 2005, a second edition of the book was published as a trade paperback, and it was updated to include information from King Kelson's Bride.