A Sorrow Fierce and Falling (Kingdom on Fire, book 3)
From the publisher:
IT’S TIME FOR HER POWER TO RULE.
As Henrietta nervously awaits her marriage to Lord Blackwood, she discovers that Sorrow-Fell is not a safe haven from the bloodthirsty Ancients. It’s a trap. So with her friend Maria and Magnus, the young man who once stole her heart, at her side, Henrietta plots a dangerous journey straight into the enemy’s lair. Some will live. Some will die. All will be tested.
In this stunning conclusion to the Kingdom on Fire series, Henrietta must choose between the love from her past, the love from her present, and a love that could define her future. The fate of the kingdom rests on her decision: Will she fall or rise up to become the woman who saves the realm?