Grace's returns from the Golden Mountain with three keys, when her sister Mary goes missing, Grace sets off with her horse pepper and Mary's horse Royal to revisits Van to look for answers, in the hope to find the remaining keys, she has a vision of the Crystal Cave that takes her on a magical journey.

Diann Maree is a writer and intuitive who lives on a farm in Queensland, Australia. The Crystal Cave is her second novel in the Grace series and is based on her personal childhood experiences growing up on a farm with horses and animals, with whom she had a very deep and special connection.