Feeling hamstrung and confined by Hollywood, writer/director Robert Siodmak returned to Europe to make most of his latter-day films. Produced in France, Magnificent Sinner stars Curt Jurgens as Czar Alexander II, with Romy Schneider as schoolgirl Katja. The Czar takes Katja as his mistress, elevating her to princess status. The romance leads to court intrigue, and is instrumental in Alexander's ultimate assassination. Magnificent Sinner was originally released as Katia; it was a remake of a 1938 French film of the same name, which starred Danielle Darieaux.
by Hal Erickson synopsis