Lioness Rampant (Song of the Lioness, #4) by Tamora Pierce

Now a knight errant, Alanna goes on a quest for a legendary jewel in this fourth and final book in Tamora Pierce’s Margaret A. Edwards Award–winning young adult series—now with a new look!

Having achieved her dream of becoming the first female knight errant, Alanna of Trebond finds herself at loose ends. She has already triumphed in countless bloody battles, and her adventures are considered legendary. Perhaps being a knight errant is not all that Alanna needs... But Alanna must push her uncertainty aside when she is tasked with the impossible.

She must recover the Dominion Jewel, a legendary gem that has enormous power for good...in the right hands. And Alanna must work fast. Her archenemy, Duke Roger, is back and more formidable than ever, putting Tortall in great danger. As she puts her hard-won skills to use, Alanna discovers through fierce combat and ceaseless searching that she can make a future worthy of her mythic past—both as a warrior and as a woman.