What is a good idea for writing an adventure book?

A good story idea is one that makes you want to sit down and write. It excites you and intrigues you and doesn't leave you alone until you write the story. Good story ideas are not delivered gift-wrapped by your muse. You have to seek them out and develop them. A good story idea is uniquely personal. What is a great story idea for you may be completely uninteresting to someone else. That's because each of us has a unique personality and history. Write the stories that only you can tell.

AnswerOne that contains either Conflict and/or Character. You have a story with both or either but not lacking in both.

New "plot bunny" websites can give you good ideas for stories.