An "international" version has been created which incorporates this film and its sequel Arn – The Kingdom at Road's End into a single cut with a duration of approximately 130 minutes.

He grows up in a monastery belonging to the Cistercians and is trained there in archery, swordsmanship and horsemanship by a former Knight Templar, the brother Guilbert.

While pursuing a band of thieves, Arn comes across the enemy of all Christendom, Saladin, and saves his life.

As Saladin marches upon Jerusalem, Arn is given the order to intercept the Saracens before they reach the city, and he and his men successfully ambush Saladin's army in a mountain pass (the ambush taking the place of the historical Battle of Montgisard figuring in the novel).

The scenes in the Holy Land use English (although historically it would have been Medieval Latin and Old French) and Arabic, including quotations from the Qur'an.

The Guardian credited the film with an exciting plot and convincing acting, and locations that "you don't get bored [of] for a second".

However, it criticised the story for not being very believable as the Knights Templar were religious fundamentalists, not "tolerant and multicultural-friendly crusaders".