The following version of the book was used to create this study guide: Shannon-Jones, Samantha, The Priory of the Orange Tree. Bloomsbury Publishing, New York, New York, 2019. Kindle AZW file.

Ead seems to be a servant in the court of Sabran, Queen of Inys, but she is actually a member of the Priory of the Orange Tree, a secret organization of mages that is sworn to kill dragons. Sabran is descended from a warrior who had battled a horrific dragon known as the Nameless One. The Nameless One will not return as long as Sabran's lineage continues. Sabran's beliefs are centered around an entire religion known as the Six Virtues. Ead, however, holds with a different set of beliefs, though she pretends to bow to the Six Virtues. Ead's purpose in Sabran's court is to ensure that Sabran remains safe, in case her line is tied to the Nameless One. Sabran is being pressured to accept a husband and have a daughter, who will then be heir to the throne. Sabran finally gives in and marries Aubrecht, prince of Mentadon. She soon becomes pregnant, but Aubrecht is killed in an attack on the royal couple. A short time later, a dragon attacks Sabran's court, and Sabran miscarries. The dragon is later identified as Kalyba, a witch who is the actual founding mother of Sabran's line. Ead and Sabran are surprised when they fall in love, and they both feel the need to try to defeat the Nameless One.

Elsewhere in this fantastical world, a young woman named Tane who lives in the East has trained to become a dragonrider. Tane works hard to reach this goal. She breaks an important rule when she finds a stranger entering her country and does not report it. However, the stranger is apprehended and Tane's best friend, Susa, is executed for her role in the crime.

Tane goes on to earn her way as a dragonrider and is paired with an Eastern dragon named Nayimathun. Nayimathun is captured by pirates.Tane knows the dragon will likely be killed and sold on the black market. Tane is exiled to Feather Island, a place where scholars spend their time studying. There, an old injury begins to bother Tane, and she discovers that the bump is actually a jewel. She feels tremendous power the moment she touches it. By this time, officials from several countries have discovered that the Nameless One will be rising soon and all humankind is in danger.

Tane has a chance encounter with a man from Sabran's court, Loth, who knows about the jewel. He tells Tane that Ead is in possession of a matching jewel and the two combined can defeat the Nameless One. Tane and Loth manage to rescue Nayimathun. Then, Tane travels to Inys where she and Ead begin to plan how to face down the Nameless One. Sabran steps out of tradition by seeking an alliance with other countries of this world as a united front against the Nameless One. Though there are ancient hostilities and fears, the leaders realize the best hope for mankind is to join forces. With this united front and a sword called Ascalon, Ead and Tane are able to kill the beast, scattering the other dragons of his forces.

As the novel comes to a close, Tane is restored to her position as a dragonrider. Ead and Sabran acknowledge that they have duties – Sabran to her country and Ead to the Priory of the Orange Tree. They plan to spend the next ten years doing this duty before going somewhere to live out their lives together