The Seventh Princess by Nick Sullivan, 1983.
Jennifer never remembers her dreams, so she doesn’t think that she’ll be able to complete the essay that her teacher assigned them to write: My Strangest Dream. While she’s worrying about not being able to finish her homework, she dozes off on the school bus on her way to school.
Suddenly, Jennifer finds herself in a beautiful carriage being driven through a dark forest. Jennifer is happy that she’s apparently going to have a dream that she can write about, so she decides to enjoy it as much as possible, trying on the beautiful gown, cloak, and jewelry that she finds in the carriage with her. Eventually, the carriage stops at a huge palace, and Jennifer comes to the realization that the carriage never had a driver.
She is greeted by Duke Rinaldo, the Lord High Chancellor of the kingdom of Eladeria. Jennifer is informed that she is Princess Miranda, the king’s adopted daughter. Actually, Jennifer is the seventh of the king’s “daughters.” There were six others before her . . . and their fates are unknown.
This is no ordinary dream. The king of Eladeria is ill, possibly bewitched. The king’s son is missing. There is treachery in the palace. People live in terror of the evil enchantress Swenhild and her harpies. Soon, they will demand a tribute: a golden-haired princess with blue eyes . . . like Jennifer, er, Princess Miranda!
The only one who seems to want to help Jennifer is her new friend, Samson the dwarf, who is the palace’s court jester. He introduces her to his friend, Prospero, who can do magic and understands more of what’s happening than most people. He tells her that her only hope is to find the Paladian Scroll and use its power. Can Jennifer and Samson find this mysterious scroll in time? It might still be possible to save the other princesses, but Jennifer worries about whether she’ll ever wake up in her own world again.