TAPA BLANDA, LIBRO USADO, RECUERDA QUE UN % DE ESTA VENTA COLABORA CON FUNDACIONES QUE FOMENTAN LA LECTURA EN ZONAS VULNERABLES. The Hero's Book. When Finn rescues Princess Bubblegum from a crumbling tower, she tells him about the secrets of the Enchiridion, a book meant for heroes whose hearts are righteous. Finn's sure the book was meant just for him. Now all he has to do is prove that he is a true hero.