Books are a delight to hold. They offer a physical experience that screens can never replicate, but their stories are bound to their pages. OneBook by Phylosofy is a paper book on which any digital content can be superimposed using mixed reality. It bridges the pleasure of the physical and the endless possibility of the digital. Our current prototype of OneBook can run on any Unity-supported device (Android, iOS) and is capable of displaying the full texts of books. It is also capable of switching between books and displaying images, animations, audio, and external and internal 3D content.