The novel is set in Caimor, a nation whose capital, Elmidde, sits beneath Paragon Academy, an elite school on floating islands where magic is tightly controlled. Human consciousness, called a Pith, can be transferred between fabricated bodies. A unique magical ability born from a person's soul is called a Codex.
Seventeen-year-old Anabelle Gage is a girl trapped in a decaying male body. At nine, a brain infection forced her mother to purchase the only replacement she could afford: a cheap, mass-produced masculine model called an Edgar. The body is breaking down, destroying Ana's senses of taste and smell. She works as a maid for Clementine, a mercenary employer, while awaiting results from her third Paragon entrance exam, which would grant a free replacement body.
Her rejection letter arrives: Ana scored 77.4 out of a minimum 95. She steals Clementine's plans for a body heist and uses her Codex, Rainbow Veil, a Whisper ability that weaves visual illusions, to cause chaos at a dinner party. Clementine reveals she is secretly a mage and uses Nudging, a spell that seizes control of another's body, to force Ana off a balcony. Ana barely survives.
That night, Ana transfers her Pith into a star-woven chassis, an ageless body from the ancient Star Prophet civilization, at the port. After escaping two Paragon students with her illusions, she is intercepted by Headmaster Nicholas Carriwitch, former chief of the Eldritch Guard, Caimor's magical law enforcement. Carriwitch reveals that Khaiovhe, the Black Wraith, who massacred thousands during a war in Shenten and destroyed a dam over Ana's hometown, is alive and leading Commonplace, an anti-Paragon terrorist movement. He offers a deal: become his mercenary and Grey Coat (a forged assistant identity at Paragon) in exchange for a new life. Ana must transfer back into her dying Edgar. She agrees.
A parallel narrative introduces the former Nell Ebbridge, who has been Ousted, a tradition in which a challenger strips a family member of their name, body, and Paragon slot through a duel. Nell's mother, Admiral Rowyna Ebbridge, arranged the Ousting. Nell wakes in a star-woven male chassis, forbidden from contacting her previous life. Carriwitch offers the same deal. Nell discovers Ana maimed her and her fiancé Samuel Pakhem, and resolves to use Ana before killing her. Taking the name Wes and a masculine identity that feels natural in this body, Nell stages a fake rescue to gain Ana's trust.
At Paragon, Ana settles into her double life as "David Chapman." She befriends Kaplen Ingolf, a warm second-year, and meets Ori Ebbridge, Kaplen's brilliant tutor. Her assigned student is Adam Weaver, the boy who saved her during the dam explosion. Adam initially seems kind, but when Ana fails a quiz, he burns off her pinky with his Codex, Palefire (white flames that erase anything they touch), and Nudges her into submission.
Kaplen shares a philosophy that becomes Ana's breakthrough: Magic is the art of changing yourself, and a Codex grows through personal epiphanies. This insight helps Ana block Carriwitch's Nudging and grow a second branch of Rainbow Veil, extending her illusions to sounds and smells. Carriwitch assigns the group's first mission under the code name Queen Sulphur.
Their target is Lyna Wethers, a former Paragon spy whose Codex, Honeypot, creates permanent infatuation that causes brain damage. Ana and Wes infiltrate a yacht party and find over 100 shattered victims below decks, including Kaplen, whose damage is permanent. Ana saves Wes by tricking Wethers's guards into killing their master. Kaplen is hospitalized, and during a visit he steals Ana's supply of Kraken's Bone, a lethal poison, using a hug as cover. By the time Ana realizes, Kaplen has taken the pills and died. Devastated, Ana vows to find Khaiovhe.
Queen Sulphur gains Nima Qasemi, a Kshatran mercenary whose Codex, Copycat, allows Nima to inhabit two bodies and copy others' skills. Nima brings Korin Nameless, a Shenti Humdrum (non-magical person) who built bombs for Commonplace under duress. Korin inhabits his grandmother's body after swapping with her to help her escape. From a clock tower hideout, the team spends months hunting Khaiovhe's associates. Korin reveals Khaiovhe used him to build a submarine to search for something ancient beneath the northern ice.
Ana grows closer to Ori, who confides she Ousted the former Nell to access Paragon's restricted library, hoping to cure her comatose sister. A major operation goes wrong when the real Khaiovhe kills professors and Guard mages with Darkfire, her lethal magical flame. On Ana's birthday, Wes tries to kill her, fearing her closeness with Ori will expose his identity as the former Nell, but he cannot strike when Ana presses her fist to his chest in the heartbeat salute, a gesture of shared survival.
Ana approaches Khaiovhe at a Commonplace stronghold, posing as a recruit while secretly signaling Adam Weaver with bursts of magic in telegraph code. The Eldritch Guard devastates the enemy, but Khaiovhe escapes and Queen Sulphur is arrested. In their cell, Nima's Copycat reveals stolen images from Khaiovhe's mind. Concluding that Khaiovhe plans to attack the Agricultural Islands, Caimor's primary food source, Admiral Ebbridge sends the nation's strongest mages south.
The threat proves a decoy. Khaiovhe summons a storm kraken that destroys the Home Fleet, while Black Arrows, Commonplace's armed enforcers, storm Paragon and kill over 200 students. When infiltrators kill Queen Sulphur's guards and the suppressive drug Null Venom wears off, the team breaks free. Ana swaps bodies with Wes and uses illusions to stab Adam at close range, but he survives and places a tracer on her that reveals her location whenever she uses magic. Carriwitch and Adam return to drive Khaiovhe from Paragon, but she kidnaps Korin and steals the Aeon Scroll, the academy's most guarded document.
Stranded with the tracer, Ana devises a final plan. She and Wes travel to a ruined northern village, where Khaiovhe, whose real name is Sophie, meets Ana in a Shenti temple. Through magical fog on the frozen lake, Ana experiences Sophie's memories and learns the central revelation: "Adam Weaver" is actually Professor Tybalt Ebbridge, Wes's supposedly dead father. Ebbridge faked his death, stole an orphan's body, and staged the dam explosion with bombs imitating Darkfire, then "saved" the village with Palefire to manufacture a heroic origin. Ebbridge caused the injury that led to Ana's brain infection and years of entrapment.
Sophie forces a body swap with Ana. But Ana anticipated this: She swallowed her remaining Kraken's Bone pills during the walk through the fog. Sophie, inhabiting the poisoned Edgar, collapses and dies. Ana, now in Sophie's star-woven chassis, is free.
Wes returns to Paragon to reclaim his identity. In an Ousting duel, Wes tells Ori the Aeon Scroll is gone and her path to saving her sister lies outside Paragon. Ori jumps, and Wes reclaims the name Nell Ebbridge. Meanwhile, Tybalt Ebbridge, still posing as Adam, is crowned the Reborn King of Caimor and announces plans to invade Shenten. Nell silently vows to destroy him.
Ana assumes the Black Wraith's identity to lead what remains of Commonplace and grows a third branch of her Codex during a train heist. She, Nima, and Kaplen's cat Cardamom settle into a beach cabin with unfinished business: rescuing Korin, confronting Adam's regime, and reading the Aeon Scroll. Ana takes her first sip of pomegranate cider, the drink she has dreamed of tasting for a year.