Because Empire of Storms is the fifth installment in the Throne of Glass series, the first four books are integral to the understanding of the plotlines, the characters, and the thematic developments. The first book begins with assassin Celaena Sardothien in Endovier, a salt mine run by enslaved people in Adarlan. Prince Dorian Havilliard and his friend, Captain of the Guard Chaol Westfall, free Celaena from enslavement in exchange for her participation in a competition in Rifthold to become the King’s Champion (the king’s personal assassin). Celaena agrees and trains with Chaol to become a better assassin, although because she was raised in Arobynn Hamel’s assassins’ guild, she already possesses numerous skills in this field. Throughout the first book, Elena Galathynius appears to Celaena and guides her to uncover the truth of the presence of the Valg in Rifthold. (The Valg are malicious, parasitic demons who possess and feed on humans, effectively killing them.) During Celaena’s journey, Princess Nehemia of Eyllwe helps her to understand the Wyrdmarks (an ancient runic language used to cast spells). Celaena seeks to win the championship, even though her main opponent was under the influence of the Valg at the behest of the evil Duke Perrington.