* BookCrossing: This is a global book sharing movement where people leave books in public places for others to find and enjoy. The goal is to get books into the hands of new readers and encourage a love of reading. You can find more information about BookCrossing on their website.
* A specific book with a "Cross" theme: There are many books with religious themes or that involve the concept of a cross in some way. You could be thinking of a book with a specific title or author, and it would be helpful to provide more context.
Please provide more details about the book you're interested in, such as the author, genre, or a brief description, and I can help you find more information.