Describe the idea of the future book
Explain the very essence of your future work as concisely as possible. Keep it to one sentence.
The sentence should contain no names or details.
For example: An orphan girl graduates from a private boarding school and becomes a governess in the home of a noble but grumpy man and tries to make friends with his family (Charlotte Bronte's "Jane Eyre").
You'll need such a concise summary in the very hypothetical case that you're stuck in the same elevator as David Fincher or Ridley Scott. Knowing how to describe a book in one sentence is an art that is worth mastering.