Who is the narrator of mixed up files?

The narrator of "From the Mixed-Up Files of Mrs. Basil E. Frankweiler" is a young girl named Claudia Kincaid. She decides to run away from home and hides in the Metropolitan Museum of Art in New York City, along with her younger brother, Jamie. The story is told through Claudia's perspective as she seeks to find her identity and explores the mysteries of art and life. The narrative also incorporates the voice of Mrs. Basil E. Frankweiler, the titular character, who adds depth to the story.