To avoid being married to a cruel king, and to save her father's kingdom from ruin, a resourceful young princess goes in search of the magic box that was stolen from her grandfather by an evil wizard.
I read this when I was in the target age group and it was a seriously perfect coming of age story, plus a little sexual awakening as well. An excellent read for Fantasy lovers with a decent hit of romance too.
When I was young and had just discovered fantasy, I used to read and reread this one. Still pretty good, but so short! Books have definitely gotten longer since then.