Books
She saw something awful in the very simplicity she failed to understand.
— F. Scott Fitzgerald · The Great Gatsby

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The sentence places simplicity beside a failure to understand it, making something apparently straightforward seem disturbing to the person observing it. 'Awful' describes her response without explaining exactly what causes it. The contrast gives the moment its unsettling quality rather than resolving the mystery.
Context reviewed