It's possible you're thinking of "Many Waters" by Madeleine L'Engle. However, this book is not a mystery novel. It's a fantasy novel for young adults.
To confirm if this is the book you're looking for, please provide more context:
* Is there a specific author you are thinking of?
* What is the main genre of the book you're looking for?
* Do you remember any details about the book's plot?
Once you provide more information, I can help you identify the book you're searching for.