Even the best plans fail.
Zayn has spent his whole life preparing for the final confrontation with the Lady of Varna, but as the day grows closer, complications multiply. When he realizes he can no longer trust his cousin, or his patron—nor does he want to get his teammates killed—it means he must finish his quest alone. But the Lady of Varna has been alive for millennia because she has a supernatural knack for avoiding even the most cunning plans. If Zayn is going to solve this impossible conundrum, he’s going to have to get help from an unlikely source and accept the price of his failures.
I found the book an excellent culmination of the series. It had a lot of emotion, both sad and happy. Zayn and company showed what they were made of. And I can't say more without possibly giving out spoilers.