Arn Magnusson (Joakim Natterqvist) is born on a farm in the western part of Sweden. He grows up to become a well educated young Knight Templar and a skilled swordsman. It is a tale not only about a truly incredible love story between Arn and Cecilia (Sofia Heflin) who became the greatest love of his life, but also about war, friendship and betrayal. However, due to political reasons, not only are these two lovers forced to be separated from each other but their faith in God is also being tested. While Arn is sent away to fight against the Saracens in the Holy Land, Cecilia is imprisoned in a monastery.