Arn: The Knight Templar (2010)

S1E2 Arn and Cecilia

Arn's betrothed, attempting to charm him, fails to realize she is actually the sister of the woman he loves. Meanwhile, Prince Knut returns from his exile in Norway, determined to reclaim his throne. He entices Arn, a skilled archer, to assist him in eliminating the usurper, though Arn's family fears this could spark a civil war. In a twist, Arn's lover persuades the bishop to believe that both Arn and her sister have committed grave sins, leading to their confinement in strict convents for 20 years. Fortunately, Arn’s abbot manages to secure a reduced sentence, allowing him to join the Knights Templar.