The Crimson Crown (Book)

The Crimson Crown is the fourth and final book in the original Seven Realms series by Cinda Williams Chima.

Summary
This is a summary provided by the author on her website, which almost matches the text on the back cover of the book:

"A thousand years ago, two young lovers were betrayed— Alger Waterlow to his death, and Hanalea, Queen of the Fells, to a life without love. Now, once again, the queendom of the Fells seems likely to shatter apart. For young queen Raisa ana’Marianna, maintaining peace even within her own castle walls is nearly impossible. Tension between wizards and Clan has reached a fevered pitch. With surrounding kingdoms seeking to prey on the Fells’ inner turmoil, Raisa’s best hope is to unite her people against a common enemy. But that enemy might be the person with whom she’s falling in love.

Navigating the cutthroat world of blueblood politics has never been more dangerous, and former streetlord Han Alister seems to inspire hostility among Clan and wizards alike. His only ally is the queen, and despite the perils involved, Han finds it impossible to ignore his feelings for Raisa. Before long, Han finds himself in possession of a secret believed to be lost to history, a discovery powerful enough to unite the people of the Fells. But will the secret die with him before he can use it?

A simple, devastating truth concealed by a thousand-year-old lie at last comes to light in this stunning conclusion to the Seven Realms series."