PS: if you haven’t read the earlier books, do that now. Don’t read on, there may be spoilers for earlier books.
Alanna is on a journey out of Tortall to rescue the Dominion Jewel and bring it back for the glory of king and country. This trip takes her out of Tortall where she meets some new friends and risks her life to bring back the one thing that might help Jon save Tortall from the wicked Duke Roger, back from the dead.
On her return to Tortall, Alanna realizes that she might have to give up being a knight errant if she wants to support Jon and her kingdom to the best of her ability. Lioness Rampant is about embracing destiny and becoming all you can be, even if it’s not what you thought it would be.
You can read the rest of the Song of the Lioness series here… or on the author’s website. There’s a followup series called The Immortals Quartet, set a few years after Song of the Lioness and following a new heroine.