The cruel prince by Holly Black.

THIS IS A SPOILER REVIEW DO NOT READ THIS UNLESS YOU HAVE COMPLETELY FINISHED THE BOOK.! DON'T

WANT TO SPOIL IT FOR ANYONE!

The story starts off with Jude's parent's being murdered and stolen away to the fairy world along with her two sisters. There she learns about the courts and the world. Jude wants to participate in the summer tournament to be knighted as an equal. Jude goes into the tournament and wins 2 out of 3 battles. Soon after Prince Dain asks her to be his spy and offers her a geas that's a protection from all others who try to glamour or enchant her but himself. As Jude takes on her first mission for prince Dain she witnesses something about Prince Cardan that makes him more real to her. She is also introduced to the court of shadows among who she will be working with. Jude continues going on with her lessons and school she and locke become close and after a party with him once she's home she opens the acorn she found in locke's mothers dress she uncovers a hidden message and starts to piece together a mystery for Prince Dain.

As days go from her trip to hollow hall Jude goes back and tries to find anything she overlooked her first time there. Before she leaves she decides to save a servant human and disobeys Prince Dain in the process. When she tries to return the to the mortal world the girl kills herself by falling off the seeds and falls into the sea and not to be found again. Soon after Prince Dain confronts Jude about what she has done and she is to wound her hand for disobeying orders. As the days go by the cermony begins. Balekin tries to take over the ceremony and to take the crown. Madoc kills Prince Dain in the middle of the ceremony. More royal family are killed. Jude kidnaps Prince Cardan and then goes home from the court of shadows and learns who taryns lover and its Locke. Jude challenges taryn for her honor back. Jude figures out the mystery acorn and that oak is really Prince Dains son. Oriana is the mystery friend who hid oak for locke's mother. Jude forms a plan with Prince Cardan and the court of shadows. Jude's Plan set in motion and prince Cardan is crowned king and is to wait until Oak is old enough to take over the thorn in seven years.