Celaena was depicted as a superb assassin right from the beginning but her destiny was not known to us. We as listeners thought that she was picked for the competition randomly but now all of us know that the choice was not random. She was intentionally picked and now Celaena knows what she has to do for her kingdom.
After facing terrible circumstances, the girl is back in the empire and this time she has returned for vengeance and she is not going to spare anyone. The empire which she held dear once has been in a bad condition for a very long time. Those who thought that they had full control of the empire will be proved wrong eventually because Celaena is coming for all of them.