Saving the Wizarding World (Ravenclaw-style)

Louise is a former Ravenclaw student. Right after graduating from Hogwarts (same year as Luna, Ginny and Hermione), she moved back to muggle London to study mathematics. Five years later, she discovers that the Wizarding World is in danger. She could save it, but she might have to forget her ethical standards. Her biggest problem, though, is her "bravery" issue. Please review! :)