The Princess and Curdie is the sequel to The Princess and the goblin, written by George McDonald.
It is a very sound book with many good morals.
It takes place two years after the first book, and Curdie is now fifteen.
He begins to doubt the princesses Great-grandmother and his heard get cold toward all the silly beliefs that the Princess had about her Great-grandmother.
In other words, he starts to turn into a grownup, and adult, who don't go believing such silly fairy tales.
But Great-grandmother Irene has other plans for him, so she sends a dove.
And through some happenings and adventures, Curdie is sent off the the town of Gwyntystorm with a grotesque dog like animal, and his mattock, to save the Princess and her father, the king, from wicked treachery.
And he has to work fast, for he doesn't have much time, and the Princess is about to be married off to some evil guy who will wrench the kingdom from the imprisoned king.
I hope you read this book.
If you don't have it, you should.
And it's written for younger readers, but teens find it enjoyable also.