French. Catherine is the king's daughter. Her mother is a Christian but her father is not. Her father finds her praying. She says that she prays to God, but he does not. He kills her with his sabre. Catherine is in heaven, but her father is not.
The description is based on the translation in the notes to MRHCreighton. - BS
There are a number of early Christian legends about this sort of martyrdom. (Interesting that the name "Katherine" is from Greek "katharos," "pure.") This one doesn't ring any bells as written, though. - RBW