Their Heavy-Hearted love letters is about Natalia fisher and Caspian night and their forbidden love. Natalia was sent to boarding school in England to pursue her love to write but in that time of her first year there she meets Caspian Fisher, the headmistress' son. They can't get caught together on school grounds, nor outside of the grounds but there's one way they can talk whenever they want..letters but over time those letters gradually turn into love letters.