Anastasia: the Czar's Last Daughter(1956)

In 1920, an unknown 24-year-old woman was fished out of Berlin's Landwehr kanal after a suicide attempt. Since she has no papers and no answers to any questions, they soon assign them to the insane asylum Dallendorf. A co-patient believes she recognizes the Czar's daughter Anastasia Romanowa - who apparently was the only one who survived the murder of the tsar's family in 1918.