Ari recalls his childhood in Surat, Gujarat. He was a shy child, but people were drawn to his appearance. While he was with his uncle, a well-dressed man wearing a golden fox pin approached him, explaining that Ari had a strong soul that attracted attention. The man transmuted mulch into an ice-cream bar and called himself Prometheus.

The next morning, the man—whose real name was Rudra Mahajan—arranged with Ari’s mother to take him to America in exchange for a monthly stipend for his family. Ari remembers his last glimpses of his sister, Kriti; brother, Dev; and father.

In Angel City, Rudra houses Ari in a luxury hotel, then gives him a lavish apartment in the Eastern Columbia Building filled with expensive clothes and books on alchemy. After his first day at school, a blonde girl named Isla—wearing a fox pin—escorts him to the Alexander Reed Gallery at the Central Library. There, other students in uniform stare at him with judgment, except for one girl with a braided crown who smiles. Rudra begins Ari’s first alchemy lesson after swallowing a shimmering white pill.

Rudra forbids family contact, citing strict Lumines rules. Over the following months, Ari writes unsent letters home, his English improving while his memory of Gujarat fades. After a lonely year, a new school semester begins. On the first day of seventh grade, Ari notices Sam in his homeroom because no one else seems to. When she sits beside him, Ari introduces himself, and Sam responds. He wants her to notice him more.

A month after the restaurant incident, during fire season, Sam contemplates the alchemy of changing seasons. She sees the Lumines men twice more, but her mother sends her to the supply closet. At home, Sam searches online for alchemy but finds nothing credible. However, she begins noticing Diamond Taylor’s name everywhere—on hospitals, at galas, in news about the Winged Towers. Neighbors gossip about Diamond’s wealth and generosity, but Sam finds no connection between her and alchemy.

In class, Sam admires Ari. He passes her a note—the first she has ever received—and they begin a daily correspondence. In one exchange, Ari writes about night becoming morning, which reminds Sam of alchemy. She nearly asks him about it but stops herself, happy to have made her first friend.

When Sam arrives home, her mother confronts her with a poor progress report and Sam’s internet search history about alchemy and Diamond Taylor. Sam dismisses her grades as unimportant, enraging her mother. Her mother retrieves Sam’s beloved stuffed animal, Rabbit, and methodically cuts it apart with a knife. Sam begs her to stop, but her mother shoves her away and continues. She throws the destroyed toy at Sam, saying Sam is too old for toys and calling her stupid.

Sam has a painful realization that her childhood innocence was an illusion. Her mother forbids her from ever searching for alchemy again. Sam silently agrees, but her mother’s extreme reaction only deepens her curiosity about what everyone is afraid of and why she cannot know.

Ari learns that alchemy must remain secret from the non-alchemical world. During a lesson with Isla, students discuss how transmuting lead to gold is possible but yields less gold due to density differences. Isla explains that alchemists use attributions—adopting names of historical figures like Isaac Newton or Moses—to appear immortal. She reveals that ancient Greek gods and Egyptian rulers were actually alchemists, and that the art spread to Persia, where the prefix “al-” was added to “khemia.”

Ari struggles to retain the flood of information. He learns the periodic table of elements, transmutation rules, and the principle that living things cannot be created from nonliving matter. While Zan effortlessly answers questions and Dominique scores highest on exams, Ari compensates for his average intelligence through relentless hard work, driven by his family’s dependence on his stipend. When other students leave at six, Ari stays until midnight, earning Rudra’s approval. Zan mocks him, saying his family will not eat if he fails.

At regular school, Ari watches Sam with envy. She retains information effortlessly but shows no interest in academic achievement. During a test, he offers to let her copy his answers, but she refuses. After class, she explains that her answers are usually not what teachers want. He laughs at her brilliant but unconventional response to a question about the butterfly effect.

They exchange letters daily, learning about each other’s inner worlds through writing. Over two years and into high school, they maintain an unspoken rule not to share personal details, both holding back even as they never run out of things to discuss.

While waiting for Ari’s late ride during a rainstorm, Sam and Ari shelter in the school library. They find a quiet nook where Ari sketches. He tells her about a secret beach he discovered. When Sam comments that everyone notices him, they share a moment of mutual embarrassment and attraction. Ari takes her hand—the first time she has touched a boy’s hand—and traces a circle-with-a-dot symbol on her palm, telling her it means perfection and he likes her the way she is. Sam commits every detail of the moment to memory.

When she arrives home, police officers are at her door. According to the official report, a gas leak caused an explosion at Mandarin Palace; her mother survived with severe burns covering half her body, but Mr. Hayes died. Sam’s mother leaves the hospital early to avoid bills and recovers at home in agony. At school, Sam withdraws. Ari expresses concern in a letter, and she nearly confides everything but fears burdening their friendship, so she tells him everything is fine. The unsaid things create distance between them, though Ari continues showing support through small gifts.

Sam’s mother struggles to find work due to her scars. When an eviction notice appears on their door, Sam writes a desperate letter to Ari about beech trees blooming before they die. He replies with comfort, saying she is about to become invincible. She agonizes over asking him for help but decides against it, fearing she will lose him.

Sam has a nightmare in which she and her mother are struggling through a storm with all their belongings, trying to reach the bus stop. They take shelter at the Odyssey Theatre, where an elegant woman with a blurred face approaches Sam, takes hold of her hand in a seemingly protective gesture, then lacerates her arm with a knife. When she wakes, she realizes that the woman in the dream was Diamond Taylor. The dream, combined with neighbors’ stories about Diamond’s ability to make anything happen, solidifies her resolve. On a premiere night, Sam lies to her mother and takes the bus to the theatre, where she finds Diamond.

From the balcony, Sam watches Diamond Taylor observing the stage show, which features performers creating fire and water—alchemy, Sam now realizes. She sees a small gold pin on Diamond’s lapel that reminds her of the fox pins from the restaurant. When Diamond and her entourage leave during the performance, Sam follows them to the back exit and hides in the alley shadows.

Diamond stands with her group, including her handsome son, Will Taylor, who wears a winged lion pin. Sam notices lookouts on the roof. She overhears them discussing business involving Lumines, Fantec, and sand—words whose significance she doesn’t yet understand. Will suddenly alerts the group and uses alchemy to brighten a streetlamp, exposing Sam. She is captured and dragged before Diamond. Will uses alchemy to produce a gun.

To save her life, Sam reveals that she knows about the rooftop lookouts and recites their entire conversation verbatim to demonstrate her sharp memory and observational skills. When Diamond remains unmoved, Sam recites digits of pi, claiming that she has memorized the number to 1,000 decimal places. She explains that she came seeking Diamond because her mother lost her job after being injured. Will dismisses Sam as too old to train. Diamond tests her further by showing her a handwritten page for a brief moment; Sam recites it perfectly from memory. Impressed, Diamond offers Sam an opportunity, telling her to come back the next day.

Isla leads Ari through a hidden door in the gallery study to a laboratory inscribed with “ORA ET LABORA.” Rudra informs him that he is ready for his first transmutation. When Ari asks about a jar of shimmering white powder, Rudra tells him he is not ready for it yet. Ari’s first task is to transmute water into ice. Isla demonstrates the simple transmutation effortlessly.

Rudra explains that alchemy requires touching the object and using a fragment of one’s soul to change the object’s form. When Ari struggles, Rudra places a hand on his chest, causing excruciating pain. He explains he can pull Ari’s soul forward, but Ari must grasp it himself. Ari collapses, but Isla helps him up. Rudra tells him the pain will dull with practice and orders him to try again.

Ari fails repeatedly for hours, leaving him physically and mentally exhausted. Rudra ends the session, saying Ari’s soul is spent. Isla comforts him, explaining that he is just learning to swim in the world of alchemy.

Will Taylor drives Sam to Red City, the Grand Central estate, warning her not to speak about what she sees. At the entrance, valets and an assistant named Hanover greet them. As they walk, Will uses alchemy to add alcohol to his drink, confirming to Sam that alchemy is real. He explains that Diamond has a talent for finding people with souls strong enough for alchemy, and Sam is there to be tested.

Will reveals that Grand Central is an alchemy syndicate, one of several secret societies. He describes other syndicates: Babylonia, whose symbol is a basilisk; Belle Epoque, whose symbol is a stallion; and Lumines, whose symbol is a fox. Grand Central’s symbol is the winged lion. Founded 30 years ago, Grand Central came about when Will’s father discovered the philosopher’s stone and his mother, Diamond, engineered it into sand—a performance-enhancing drug. A new class of alchemists called philosophers was created to produce sand, though the arduous process shortens their lifespans. Other syndicates now also produce sand, and a truce protects the valuable philosophers from being killed.

Will explains that money is power. Sam realizes success is about bending rules, not just hard work. They tour the vast estate, including staff quarters, visitor hotels, and personal residences. At the Observatory, the alchemists’ college, the courtyard floor is a mosaic of hundreds of different elements.

Will gives Sam sand dissolved in water. After drinking it, her senses sharpen dramatically. He blindfolds her and explains the concept of “prima materia”—that all matter is energy. He makes her kneel and touch a tile, asking her to identify the element by feel alone. Empowered by sand and remembering Ari’s encouraging words, Sam taps into her soul and correctly identifies silver, then continues identifying other elements.

When the blindfold is removed, Diamond is watching. Will informs the professor that Sam will be her new student, revealing that no untrained apprentice has ever passed that test before. When Sam explains her family’s financial situation, Will gives her an envelope of cash and promises her $2,000 per week, telling her money will never be a problem again.

Ari returns to the lab for more training. He endures the same painful process and fails repeatedly over several days. At the end of the first week, Rudra suspends his family’s stipend to motivate him. At school, Ari is distracted; Sam helps him keep up, and he is tempted to confide in her but does not. Zan continues to bully him. Stress knots Ari’s chest as he worries about what his family must think of the sudden halt in payments. Rudra grows increasingly impatient, his voice more clipped with each failure.

Ari dreams constantly of his family. Once, he dreams of Holi celebrations in Surat and wakes to realize he missed the holiday entirely. During another session, the pain becomes so intense that Ari collapses, unable to continue. Rudra becomes enraged and transmutes a knife from the table. He threatens Ari, calling him worthless and implying that he will be disposed of if he fails.

The threat fills Ari with calm rage. He recalls Sam’s words about becoming invincible through suffering. He places his hand in spilled water and successfully calls upon his soul, freezing the water instantly. Rudra is thrilled, realizing Ari performs best under life-or-death pressure. Ari defiantly tells Rudra he is not worthless. Rudra grabs his chin and declares that Ari will now become a true alchemist, an exquisite blade.

Ari becomes accustomed to the pain and excels in his studies. He learns about sand and receives private tutoring from Isla. As he matures into high school, the constant loss of soul fragments leaves him ravenous and exhausted. At school, his enhanced charisma makes him very popular, though he declines social invitations. His mysterious refusal only increases his mystique, but he only feels like himself with Sam.

In junior year, Sam asks him to the spring formal, but he refuses. That night, he writes a long confessional letter revealing everything about his alchemy training and his love for her, but tears it up out of shame. The next day, he gives her a simple note saying he would have danced with her.

One night while studying late, Ari witnesses Rudra dragging a terrified, sobbing Zan through the study. To prevent Zan’s escape, Rudra transmutes the main doors into a solid wall, then drags Zan into the hidden lab. Ari hears Zan’s cries suddenly cut off. Rudra emerges alone, restores the doors, and looks directly at Ari’s hiding spot before leaving.

The next day, Zan is gone. Isla announces he will not be returning. Ari confronts Isla, who reveals that Zan was caught leaking Lumines secrets to a member of Grand Central while drunk at a party. She warns Ari that the syndicate rivalry is deadly and betrayals are not tolerated. Ari realizes that failure or betrayal will cost him his life. There is no walking away from Lumines.

Sam’s new salary drastically improves her life. She lies to her mother, claiming to work at a law school for $4,000 monthly while secretly depositing another $4,000. Their struggles end—they get health insurance, a new apartment, a car, and restaurant meals together. Sam also buys herself luxuries and uses a private apartment at Red City. Ari notices her new clothes, sensing a change. Her mother becomes suspicious of Sam’s long hours, creating distance between them.

At the Observatory, Sam is isolated and ignored by classmates. She finds solace in the estate’s library, the Bibliotheca Aeternus, devouring books obsessively. She wants to tell Ari about her new life but retreats when she sees him with another girl. Sam quickly surpasses her class, memorizing all course material for the year. She asks Hanover about Will, hoping for greater challenges, but is told he is traveling.

Months later, Will appears in her classroom and shares a brief, intense glance with her. Sam goes to his house and tells him she is bored, wanting a real challenge. Will is dismissive, telling her to be patient and prove herself capable. He stands intimidatingly close before dismissing her. She leaves, silently vowing to get him proof.

One evening, Sam practices forbidden bioalchemy on leaves in the courtyard. A classmate, Nicolas, finds her and recognizes the partially transmuted leaf. He reveals that he is training as a philosopher and keeps the leaf as evidence. His tone becomes aggressive. As she tries to leave, he grabs her arm and tears her blouse. In fear and rage, Sam instinctively grabs his neck and performs a transmutation, giving him a severe burn. She is horrified but also feels dark satisfaction as she screams for help. She realizes she will never be forgotten now.

The next day, Nicolas is absent, and all students stare at Sam. Will is waiting for her after class. He explains that her untrained bioalchemy attempt accidentally created white phosphorus, a chemical weapon, on Nicolas’s skin. His main concern is that she might not survive her own unsupervised attempts. He tells her alchemy requires understanding oneself, not just memorizing formulas.

Will offers her a chance to prove her value and gives her a box from Diamond containing sand and a note urging her to become her true self. Sam takes a pill. Will leads her to the Hotel’s basement Confession Rooms, where a bound, naked man named Mr. Clarkson lies on the floor. Will explains that Clarkson is a Grand Central manager suspected of embezzling and meeting with someone from Lumines.

Will interrogates and tortures the man with elemental alchemy, then orders Sam to transmute away a patch of his skin. She initially refuses. Will reveals the truth: Lumines caused the restaurant explosion that injured her mother because Mr. Hayes owed them money. Will uses this information to manipulate Sam, telling her to remember who hurt her. Sam wonders if her mother knew about alchemy all along.

Fueled by rage, Sam performs transmutations on the man twice, turning his skin to coal and then glass as he screams. She feels numb, having crossed an irreversible line. Will tells her that a part of her soul wanted to hurt the man, that she cannot be forced into a transmutation. He admits he knew about her mother from the beginning but withheld the information. Will graduates her from her class, saying he will train her himself.

Ari is taken to a Beverly Hills clothier where Rudra informs Ari he will meet Alexander Reed. A tailor fits Ari for an expensive suit while Rudra nervously micromanages, revealing his fear of Reed. Rudra tells Ari that his education is now becoming a true apprenticeship. On the night of the meeting, a team prepares Ari’s appearance. Rudra gives him his first pill of sand.

At a charity auction at the Getty Museum, the sand sharpens Ari’s senses and enhances his charisma. He becomes the center of attention, handling social pressure with newfound ease. They meet Alexander Reed, who appears more powerful and intimidating than Rudra. To test Ari, Reed orders him to perform bioalchemy on Isla, changing her hair from blonde to black. Ari successfully performs the difficult transmutation.

Reed officially welcomes Ari into Lumines, pinning a fox crest to his suit and giving him the attribution “Shakespeare.” He tells Ari he must leave his old life behind. Ari thinks of his family and Sam. Rudra tells Reed that Ari is the weapon they need to destroy Grand Central.

After the party, Isla takes Ari to a Lumines-owned bar. She explains that he is Lumines’s most promising alchemist in decades and that his specialty will be bioalchemy—manipulating powerful people through social interaction. At her apartment, Isla initiates sex, using alchemy to heighten pleasure and endurance. She teaches him how to use bioalchemy during intimacy. While they have sex, Ari hallucinates being with Sam. As he falls asleep exhausted, he knows he is going to miss Sam deeply.

During finals week, Diamond summons Sam to Red City. Her salary has increased to $20,000 monthly. Sam meets Diamond and Will in the Observatory courtyard. Diamond questions Sam’s true motivation for seeking her out. Sam realizes her motivation is not just money but a desire for greater things and for justice. Diamond explains the terms of loyalty to Grand Central, speaking of a coming war with other syndicates. She pins the winged lion crest on Sam’s suit and gives her the attribution “Mozart.”

On the last day of school, Ari invites Sam to his secret beach. Sam decides she is ready to tell Ari everything about her new life. At the beach, Ari asks if she ever feels like she does not belong in Angel City. Sam explains that the city is all she has known, while Ari reveals that he remembers his life before. As Sam prepares to confess her secret, Ari speaks first, telling her that he is leaving Angel City and will be traveling extensively.

Crushed, Sam loses her nerve. They do not kiss, though the moment hangs between them. When Ari touches her cheek gently, Sam feels a curious, soothing calm settle over her, and her skin tingles, a subtle sign of his alchemy. He promises not to forget her, though they both know that such promises are unreliable. Sam realizes the wide-eyed girl Ari knew is about to disappear forever, just as he does not realize how much he will change. They sit together until sunset, making promises they will not keep. Five years will pass before they meet again.