If the example I gave is what you mean by the question, then it would be a comma. I hope this helps!
Ex:
"It gives us goosebumps",
Answer:
Early Bird catches the worm.
Explanation:
Because it means the one that arrives first has the best chance for success.
You didn’t post any question : step by step explanation
If there is nothing specific the book needs to be abt then maybe Abt your OCs lives or real world problems to spread awareness?? Just a thought