Empire of Storms follows Aelin Galathynius, who claims to be the rightful heir to the throne of Terrasen. In an effort to retake the throne with the help of allies (including her love interest Rowan, her cousin Aedion, and Lysandra), Aelin journeys back to Terrasen after spending several years in hiding. While in hiding, she moved past her previous identity, Celaena Sardothien, a ferocious assassin. She is also now an incredibly powerful Fae warrior with the tools to reclaim her throne. Preceding her return, Aelin thought that she would be welcomed back into the kingdom with open arms. However, that is not the case: royalty rejects her claim to the throne.
The novel also follows Manon Blackbeak, who is the heir to the Blackbeak witches' clan. From a very young age, the people around her inculcated her with a sense of duty to the clan she would be leading. That clan of elite witches forces Manon to make a choice: will she attend to her duties as a leader or fight against the cruelty of the Ironteeth witches?
Meanwhile, in her efforts to regain her throne, Aelin begins to engage with those around her politically. She hopes that she can find a political situation to her situation rather than a confrontational, violent one. She seeks alliances with other territories and lords to help effectuate her goal, including with Lady Elena, a powerful noblewoman.
Aelin's plans come to fruition after she devises a strategy involving Lysandra's shapeshifting abilities to divert the attention of their enemies. Their struggles culminate in a significant naval battle against Erawan's forces (her enemy). However, their victory is short-lived. Maeve tricks and captures Aelin, preventing her from controlling people.
