By far, this is the most complex and absolute BEST book of the series. Anyone who can't find it in their heart to have some kind of emotional attachment to Celaena by this book may have some psychological disorder. I just feel like this series keeps improving with every installment and I'm blow away that it continues this way since each book before I always thought would be tough to beat. In this particular book Celaena has been sent off to Wendlyn on a mission for the King, even though Celaena has ulterior motives for the journey. She's in a completely different setting which allows us to meet a handful of new characters. We get to meet Queen Maeve of the Fae,a cunning and cold blooded leader, who according to Celaena is "older than dirt", but knows everything. Rowan, who has a blood born oath with Maeve, becomes another big player in this story. He's dark, brooding but every bit as fierce and cunning as Celaena. My absolute hands down favorite new addition is Manon, a witch. In this side story, she is learning to ride wyverns. Instantly, I felt a connection to this young warrior. She's strong, a force to be reckoned with, and someone who definitely should be feared. However, I sensed despite all this, she still had a good, pure and compassionate side to her character. I feel like she will begin to play a much bigger roll in upcoming installments. Scorcha, a healer, who slowly becomes a love interest of Prince Dorian is another character I learned to love and admire. She's a quiet beauty who steals the heart of our Prince. The old characters Chaol, Dorian and the nefarious King of Adarlan still exist. Plus we finally get to meet The Wolf, Aedion, who ends up playing a much bigger part in this story. We learn a lot of his sercrets and he quickly becomes someone I really enjoyed reading about. Even Fleetfoot, Celaena's dog remains present in the current story. 
 The setting for Heir of Fire was in Wendlyn, pacing was fast. I LOVED how so much was going on. Sometimes, in the beginning, it was a little challenging to keep it all straight, but eventually it all became much clearer. Writing is just engaging and beautiful, with prose I found myself getting lost in. World building continues to improve with each book, building upon itself in each story, brick after brick. The narrative is told in third person primarily from the perspective of our heroine Celaena Sardothein. 
 Overall impressions of this story are that this book was fabulous. I just don't see how Maas can continue to improve from here. My favorite aspects of the story were the deep, complicated problems and complex plot, the immense growth and development of the characters, the detailed information we gleen from some of the character's difficult pasts, the fantastic side stories and especially the new additions of the witches and wyverns. This story had me captivated from start to finish. Its the type of book that you hate to put down and night and look forward to picking up again the next day. There wasn't ever a dull moment or a lull in this book. It was pure awesomeness from start to finish. The ending was extremely nail biting, action packed and even tear-jerking in some parts. I felt like Sarah did a much better job in this one of creating a great amount of tension near the end, but without ending on an evil cliffhanger like in book #2. I just hate those! I felt like this book had some closer, which I needed. However, I still can't wait to get my hands on #4. I seriously don't know how I'm going to wait for an ENTIRE year for the next book!