have (one's) nose in a book
To be reading a book. Often used of people who always seem to be reading. He's had his nose in a book for the entire camping trip. I wish he would take a break and enjoy the scenery. Poor Mary is so shy. She just has her nose in a book wherever she goes.
have your nose in a ˈbook, magaˈzine, etc.
(informal) be reading something and giving it all your attention: She’s always got her nose in a book.