Is 4-5k words too long for a chapter (assuming the book is roughly 100k words)? Also, a friend of mine told me about a book his Danish Grandfather wrote years ago. The book was published in Denmark and then America. Both of us have spent dozens of hours scouring the internet but nothing can be found of the book (we only have a general description and the author's name, no title). Would writing something based on the same scenario be considered plagiarism in any form? I've never read the story but understand the basic concept and it's not anything I've ever heard or seen before and I'd love to try my hand and creating something with the same premise in mind.