Birger Jarl
There is also a fourth novel entitled "The Heritage of Arn" (2001)"," original Swedish title "Arvet efter Arn." It is as a direct follow-up to the trilogy, depicting the rise of Birger Jarl, who came to rule during the formation of Sweden and is the supposed founder of Stockholm. In Guillou's fictional universe, Birger Jarl is the grandson of Arn Magnusson.