backstory vs cover story

backstory

noun
  • A fictitious account of a person's history designed to conceal their actual history and motives. 

  • The previous life and experiences of a person, especially a character in a dramatic work, but also a real-life person. 

  • A prequel. 

cover story

noun
  • A fictitious account that is intended to hide one's real motive. 

  • A story included in a publication that is highlighted on the front cover. 

How often have the words backstory and cover story occurred in a corpus of books? (source: Google Ngram Viewer )