It has been great to work with a passionate writer Sonia!
This is the summary of the book by her.
Luca found a diary with written "Journey of a compass comet". Luca works in a book shop, but he is a really creative person and his hobby is painting.
Inside the diary is written Mira's story (her adventures, stories of love and friendship). She is a photographer who followed her passion and she moved to Milan to teach photography. She wrote the diary during her journey to Santiago de Compostela and she gave it to a stranger couple during her flight back. Then couple passed this diary to another reader and from one person to another person until reach Luca.