The book narrates Aerin's evolution from the shy, retiring daughter of the King of Damar to the heroic queen who protects her people from the demonic Northerners.

However, just as Arlbeth prepares to ride north, a messenger arrives bearing news that the last of great dragons, Maur, has reappeared and is terrorizing Damar.

After a tremendous battle, Aerin narrowly defeats Maur, claiming as her trophy a red stone left behind when his body burns itself to ashes.

When Aerin is fully recovered, Luthe sends her north with the dragon's red bloodstone and Gonturan, The Blue Sword, to challenge Agsded.

Using Gonturan and her army of foltsza and yerigs, and giving the Hero's Crown to Tor, she helps defeat the Northerners, but at the cost of many lives, including Arlbeth's.

The Hero and the Crown was part of a shift in young adult fantasy in the late 20th century: "a sudden flowering of heroines", according to a 2016 history of the genre.

[2] She was influenced by the heroic quests of J. R. R. Tolkien, but felt disappointed by the women in his work with the exception of Éowyn, a character who disguises herself as a man to be able to fight.

Through Aerin's bond with a horse named Talat, the story features the motif of a tomboyish female lead with an animal companion, a recurring trait in McKinley's work.

[12] In a retrospective essay about the Newbery Medal-winning books from 1976 to 1985, literary critic Zena Sutherland wrote, "Long and intermittently intricate, the story impresses by its scope and sweep and by its narrative power rather than by the depth of its characterization; it has many familiar folkloric elements, but they are put together with considerable industry and some panache.

"[13] In a 2016 essay for Tor.com, novelist Ilana C. Myer wrote, "Ultimately, the world McKinley creates through her inimitable prose, together with a memorable heroine, ensure that The Hero and the Crown remains a fantasy classic.