story based on published work
by brya franks
Question: I want to take up the story from where a published work finishes, as I believe the ensuing events could be dramatic and emotionally compelling. The published work was made into a film with a dark and dramatic ending and you wonder what happens to the main character going forward.Answer:
I hope the work you have in mind is in public domain, otherwise you would be infringing upon the author's copyright. It would be plagiarism to write a story using characters or a story world created by another writer.
Of course, if you just want to write fanfiction that will not be sold for profit, or is simply for your own enjoyment, then the original author can decide not to prosecute you. (Most authors and publishers don't prosecute writers of fanfiction unless they try to make money from their work.)
If a book is in public domain, which usually is the case if the author has been dead for over fifty years (75 in the US), then you are free to write all the sequels you like. This is why you will see plenty of books based on Jane Austen's works, and why there are numerous modern stories about Robin Hood and King Arthur. The fact that Sir Arthur Conan Doyle's stories are moving into public domain explains why there have been several recent adaptations of Sherlock Holmes.
In fact, books based on classic stories have an advantage in terms of sales, in that many readers are already fans of the characters.
But if the book and film are recent, then they are most likely protected. After all, the author might want to write their own sequel and has a right not to have their profits undermined by other people publishing books based on their creations.