
The Will of the Empress

The Will of the Empress, previously titled "The Circle Reforged", is a standalone fantasy novel by Tamora Pierce, a continuation of the story of the quartets "Circle of Magic" and "The Circle Opens".
Plot summary.
Empress Berenene.
The primary plot of the novel is the struggle of Sandrilene fa Toren, a half-Namornese noblewoman, against her cousin, Empress Berenene of Namorn; Sandry had inherited the vast Namornese estate of Landreg from her mother, who had accustomed her to receiving a yearly income from the estate while rarely visiting it. Empress Berenene, who wants to keep the revenue from the estate within Namorn, repeatedly invites Sandry to visit her court in Dancruan while levying increasing taxes from her estate. When Sandry realizes that the Empress has been threatening Namorn's amicable trade with Emelan, she decides to accept the Empress's invitation and use the visit to visit her estate and Namornese family.
Sandry's uncle, Duke Vedris of Emelan, asks her childhood companions Daja Kisubo, Trisana Chandler and Briar Moss who have just come back from their travels to accompany her in lieu of a company of guards, a gesture both discourteous and ineffectual. Though their friendship with Sandry and with each other has become strained since their return to Summersea after years of world-traveling, Daja, Tris and Briar agree, and the four travel to Namorn together.
While there, they learn of the Western Namornese custom of bride kidnapping, which entails a man kidnapping a prospective bride and holding her captive until she agrees to sign a wedding contract. While the so-called "horse's rump" wedding is usually only used to bypass reluctant families or out of a sense of adventure, some marriages are forced, and the custom remains legal. Empress Berenene has never attempted to illegalize it despite having twice been kidnapped, because she believes her ability to escape both times means that only weak women would allow themselves to be forced into a marriage they don't want. When he hears of this, Briar comments that the Empress's captors are unlikely to have used the same level of violence as a common woman might encounter.
Because of their power and renown, Empress Berenene decides that Namorn stands to benefit if she persuades all four mages to remain in her court, in addition to Sandry and the funds from her Namornese estate. She offers Tris a position as a court mage with a large salary and benefits including access to the Imperial library, attempting to appeal to her merchant upbringing and her known bibliophily. She appeals to Briar by inviting him to her fantastic private greenhouses, offering him unlimited access as her personal gardener and showing him public favor, including an earldom. To entice Sandry to remain in court, she sends an entourage of four young nobles to escort her to "Clehamat" Landreg, including Finlach "fer" Hurich and Jakuben "fer" Pennun, who openly compete in their courtship of Sandry. Daja develops a relationship with Berenene's beautiful seamstress, Rizuka "fa" Dalach, which is encouraged by the Empress in order to keep Daja in Namorn.
When Fin, frustrated by Sandry's reluctance, kidnaps her with the aid of his uncle, locking her in a magic-proof box in the Julih Tunnel, a secret part of the castle, Sandry reconnects her magical bond with Briar while he is at a dance with Caidy, calling out to him for help. Briar and Tris succeed in extracting Sandry, and they decide to leave Namorn despite Empress Berenene's efforts to dissuade them and the incarceration of Fin and his uncle, until then the head of the Dancruan Mages' Society. The Empress then orders Ishabal Ladyhammer, her most powerful war-mage, to prevent the four from leaving to save face, and Ishabal casts a curse on Tris, causing her to fall down the stairs and fracture most of her bones.
The injured Tris insists that Sandry, Daja and Briar travel ahead of her, and she catch up to them when she recovers. Halfway to the border with Anderran Sandry is again kidnapped, this time by Pershan "fer" Roth, whose proposal of marriage she had refused shortly before leaving Dancruan, and Quenaill Shieldsman, a powerful court mage and Shan's rival for the Empress's attentions. 
Quen lays a powerful sleeping spell on Briar and Daja and magic-dampening spells on Sandry. Briar uses smelling salts he calls "Wake the Dead" to wake up Daja and they start to go after Sandry when they are confronted by Quenaill. Briar and Daja engage Quenaill, draining him until the spells on Sandry wear off. When Sandry wakes up, she is covered in charms to prevent her from using her magic. These charms are tied to her with ribbons and she is thus able to free herself. Sandry then uses thread magic to unravel her captors' clothing and cocoon them in the resulting threads.
After meeting up with Daja and Briar again, the party continue to the border. Aware that the empress may attempt to stop them, they send ahead their traveling companions and send their guards home. At the border, they are confronted by Ishabal Ladyhammer. She raises a barrier against them, but Sandry uses the circle of thread that binds them together to combine their powers. Tris, who had been travelling behind, magically accesses the ring from a distance, allowing the four mages to use their amplified power to shatter the border barrier. The thread circle disappears and all four now have a circular lump in their hand. Having invested much of her power in the barrier, Ishabal is magically drained when she leaves without attempting to stop Tris from crossing.
"The Circle Reforged".
The original title of the novel, "The Circle Reforged", refers to the reforging of the four protagonists' friendship. In the year of the "Circle of Magic" quartet, Sandry, Tris, Daja and Briar live together and develop a strong friendship that manifests itself magically as a bond that allows them to communicate telepathically and causes their magical abilities to cross over from one to another. In "The Circle Opens" the four are separated, although their bond is clarified when they refer to each other as siblings or foster-siblings. Sandry remains in Summersea, living with her uncle in the Ducal Citadel, while Briar, Daja and Tris travel the world with their respective teachers. When they return, Daja after two years and Tris and Briar after four, the experiences they had while apart lead them to close their mental connection to each other, a representation of the distancing of their relationship. Sandry, feeling betrayed first by having been left behind, then by the telepathic wall, reciprocates in the same manner.
Throughout the first few chapters of the book the four mages fight frequently. Briar and Tris are invited by Daja to live in her new house, with Tris taking over housekeeping duties to assuage what she perceives as charity from her wealthier friends. Daja withholds the extent of her hurt at not being able to return to Winding Circle as well as her experiences with the arsonist Ben Ladradun during "Cold Fire". Tris lies about her newly learned ability to scry on the wind because of the ill treatment she experienced from other mages who found out. Briar refuses to discuss his experiences of war in Gyongxe and his resulting post-traumatic stress disorder with anyone but Rosethorn, his teacher and traveling companion.
Sandry and Daja are the first to reopen their mental connection, ending their estrangement. Later in the book, Briar and Tris open their connection with each other. Some time later, Sandry telepathically calls out to Tris and Briar when she's trapped in a box, nearly paralyzed by spells that bind her magic and her own fear of the dark. Eventually, their telepathic bond is completely restored, though they maintain their ability to screen their minds when they choose to. The bond, and the circle of thread that represents it, serve them in a joint magical working to breach the barrier on the Namorn-Anderran border during the book's climactic battle; once complete, Sandry finds the thread gone, and each of them is left with a scar on their right palm resembling the four lumps in the thread that had represented their magical identities.
In the post-climactic scene, each of the four reveals the secret that they had been keeping, and Briar introduces his sisters to a mental recreation of Discipline Cottage, their former home, which he had created and used when he wanted to feel safe.
Romantic sub-plot.
"The Will of the Empress" is the first book set in Emelan to involve the protagonists in a romantic sub-plot. While previous books alluded to romantic relationships between the adult characters, none of the four main characters were shown to have romantic interests.
Sandry's visit to Namorn is punctuated by Empress Berenene's desire to see her marry a Namornese nobleman. She is courted by Jak and Fin, whose advances she rebuffs while maintaining a friendly acquaintance with them. She develops feeling for Shan and responds to his less public courtship, but when she learns that he's sexually involved with Empress Berenene, she doesn't pursue the relationship and rejects his offer of marriage. After Fin's incarceration Jak learns that Sandry is leaving Namorn and visits her before she leaves, when she tells him that she enjoys his company much more as a friend than as a suitor.
Daja meets Rizu, the Empress's Mistress of Wardrobe, developing an infatuation with her and commenting on her beauty and flirtatiousness. Her feelings remain unacknowledged until Rizu makes the first move and kisses her, resulting in awkwardness on the part of Sandry, who telepathically senses the kiss and is flustered by the rush of Daja's emotions while dancing with Fin. Daja and Rizu's relationship quickly becomes sexual, and is discovered by Briar when he finds Rizu in Daja's bedroom one morning naked. During their short relationship, Daja develops intense feelings for Rizu and shows a desire for her to be accepted as part of her siblings' inner circle, while they are reluctant.
When Daja prepares to leave Namorn she asks Rizu to return to Emelan with her and is heartbroken by her refusal; during the ride to the border she's shown to carry a small portrait of Rizu in her pouch. After Daja leaves, Berenene comments on Rizu's low spirits since her lover's departure.
Briar, coping with an unspecified war in the country of Yanjing, tends to romance as many women as he can, mainly Caidy. He reassures the others that he takes droughtwort, a plant that renders the eater temporarily sterile. He has vivid nightmares of the war in Gyongxe when he sleeps alone.