Teenage Binti nervously pokes at her finicky transporter, praying for it to lift her luggage. When it does, she breathes a sigh of relief—now, she can make it to the station on time. She knows that her family will be distraught when they realizes she’s gone, but by the time they figure it out, she won’t be on Earth anymore. Binti boards the shuttle and tries not to notice her braided hair hitting people in the face. She rolled her braids in otjize that she made especially for the journey, but she knows she must look odd—she’s the only Himba on board. As the shuttle pulls out, Binti looks back and can see her parents’ huge house, the Root, rising up out of the city. She asks herself what she’s doing.
At the launch port, Binti is immediately overwhelmed. She’s uncomfortably aware that she looks undeniably Himba. Typically Himba don’t leave their ancestral land because it’s extremely important to them—that’s why they cover their bodies in otjize, which is made from clay. Binti feels alone and unsure, and she knows her life will never be the same. She reasons that it was never going to be normal, though; that would’ve been impossible after being offered a full scholarship to Oomza Uni far across the galaxy to study mathematics. A security officer does a deep scan of Binti’s astrolabe. This is invasive, but Binti is surprised when the officer congratulates Binti and says that her people are proud of her—he learned from her astrolabe about her acceptance to Oomza Uni. Next, Binti crosses the station to board, noticing that almost everyone around her is Khoush. In line, a group of Khoush women tug on Binti’s hair, sniff her otjize, and are surprised it doesn’t smell like feces. One woman sniffs that “dirt bathers” are filthy. Binti ignores them. The security guard scans Binti’s body and pulls a device, known as an edan, out of her pocket to inspect. Binti isn’t sure what it does; she found it in the desert. The guard isn’t well-educated, so he lets Binti on the ship without a fuss when she makes it clear she has more education than he does.
On the ship, Binti finds a group of 12 other new Oomza Uni students, all Khoush and about her age. A technician shows them parts of the living spaceship, and then the stern group leader calls Binti out for her Himba appearance. Over the next few days, Binti is uncomfortably aware that she’s the only Himba. However, Binti also discovers that her future classmates are true friends. They’re just as interested in math, science, and education as she is, and they bond by holding treeing competitions. Binti develops a crush on a boy named Heru, who is the first to notice that her hair is braided into a specific coded pattern that reveals her family’s history. One day during dinner, five days before the ship is supposed to land, Binti holds onto her edan and watches, horrified, as all her friends explode and die—jellyfish-like Meduse have infiltrated the ship. Binti prays to the edan to protect her and wonders why the Meduse attacked. They have old issues with the Khoush, but the two groups agreed to not attack each other’s ships.
In her grief and confusion, Binti thinks of her family at home. No one wanted her to leave—even her best friend Dele laughed after congratulating her on her acceptance. However, Binti has wanted to attend Oomza Uni since she learned what a university was. She’s a “master harmonizer” who can understand math in a different way. For her, the future isn’t just taking over her father’s astrolabe workshop—it’s following her destiny across the galaxy. Binti opens her eyes and notices a dead Meduse in front of her. When she thrusts the edan at another Meduse, it jerks back. Binti begins to tree to calm herself, grabs food and water, and heads for her room. She collapses on the floor and attempts to report an emergency, but the Meduse must be controlling signals in and out of the ship. Binti discovers that she’s five days from Oomza Uni. She spends the next few days pacing and crying, trying not to think about how security at Oomza Uni will blow up the ship.
A knock at the door startles Binti. She hears angry hisses when she picks up her edan and shrieks for the Meduse to leave her alone. She decides to accept her death, but as she holds the edan, she suddenly understands how to use it. Binti rolls more otjize into her hair, and when she hears another knock, she begins to rub otjize onto the edan. She notices a button, presses it, and then hears “girl” from the other side of the door. This nearly makes her scream. She can understand everything the Meduse say, and her hands are stuck to the edan. Voices outside argue, saying that Binti and the edan are evil and that they want to kill her. When she hears that one Meduse is named Okwu, Binti calls to Okwu. She tries to tell Okwu that she’s not evil or violent like other humans, and she reiterates that she doesn’t know how they can speak.
Binti falls asleep, but she wakes up to the Meduse sucking her door off the frame. One flies at her; a tentacle brushes her arm and its stinger begins to shrivel. Okwu tells Binti that she’s evil and leaves. Okwu returns several hours later, demanding to know more about Binti’s otjize. Binti notices that Okwu’s injured tentacle seems better where it brushed her otjize. Okwu demands the otjize, but Binti refuses—the otjize is her culture. After a while, Okwu offers to bring her food. Binti struggles to eat with her hands still stuck to the edan. Okwu observes that she’s not a normal human, since she has okuoko. Binti is confused but ascertains that Okwu is referring to her thick braids. Okwu laughs and confirms this. As they talk, Binti realizes that Okwu sounds like her brother Bena—Okwu has every right to hate humans, but it doesn’t know what it’s talking about. Okwu is also young and reminds Binti of herself. Okwu finally reveals why the Meduse attacked: their chief’s stinger was stolen and is now at Oomza Uni in a museum. Okwu isn’t concerned when Binti insists that the Meduse will die. Suddenly, Binti shrieks that she’s a master harmonizer and asks to advocate for the Meduse. She’s certain that she can persuade the educated people at Oomza Uni to give back the stinger.
Okwu isn’t certain, but it later leads Binti to the Meduse ship and points out the chief. Both Okwu and Binti are risking their lives by doing this. Binti can see that some Meduse are walking astrolabes—their technology is advanced. Binti bows to the chief and explains about astrolabes. She realizes that she can use the edan because she’s a master harmonizer and asks to advocate for the Meduse. She can feel a stinger pressed to the back of her neck and makes the case that all the Meduse will die if they try to get the stinger back violently. The chief and Okwu, however, say that they need Binti to show she’s serious by dropping the edan and making herself vulnerable. Binti painfully pulls her fingers off the edan. She sees a current running between herself and the Meduse and feels a stinger plunge into her neck. To the reader, Binti says that she died when she left home because she incorrectly assumed she’d be able to return and continue her life as though nothing happened. She had to die again to earn the respect of the Meduse—and now she knows that the Meduse aren’t senselessly violent but truthful and honorable.
Binti can smell home. She wakes up, covered in a fresh layer of otjize, with the edan on her lap. Most of her otjize is gone, and the ship will land in an hour. Binti watches the multicolored planet come into view. She struggles to stand when they land, but Okwu appears and warns her to be careful. Binti realizes that she can actually hear Okwu’s voice. It says that the sting didn’t cause this; Binti can hear because she’s a master harmonizer. It also says that they used otjize to heal their sick, and they’ll always remember the Himba. Binti leaves the edan behind as she follows Okwu to join the chief. Before Binti left her room, she rolled fresh otjize into her braids. Her head tingled and she remembered how as a kid, she and friends snuck out and washed all their otjize off one night—it was horrifying but thrilling. Binti considered washing her otjize off to start at Oomza Uni, but she decided against it.
Human soldiers meet Binti, the chief, and Okwu. The guards lead them to a large blue room filled with professors, where a professor named Haras introduces itself and invites Binti to speak. Binti tells the professors about the Himba and their otjize. It’s annoying but somewhat comforting when several professors chuckle—prejudice exists everywhere. Binti shares what happened on the ship and notes that no one has studied the Meduse up close—except for, possibly, in the case of the chief’s stinger. Binti tells them how to solve this peacefully. The chief speaks, and then the professors turn away to talk amongs themselves. Binti sits down until the professors turn back to them. In the Meduse language, Haras apologizes to the chief. It promises to expel the researchers who stole the stinger and give back the stinger. Binti falls from relief, but Okwu steadies her. Then, Haras congratulates Binti and asks her to work with a professor named Okpala to study her edan. Haras also invites Okwu to stay as the first Meduse student. The chief is shocked and pleased. Binti feels alone and like she’s a part of history. She wonders if her family would understand. Okpala asks if Binti will return home, since the Himba don’t like outsiders. Binti is offended, but then she sees that her braids have turned into blue okuoko, and she drops into a meditative state. Okwu and the chief explain that this was the only way to allow Binti to understand them and make it clear that she’s not a prisoner. The chief says that Binti will always be a friend of the Meduse, but Binti wants to scream. The group heads for the weapons museum, where the chief reattaches its stinger. Only a thin scar remains, a mark of what humans at Oomza Uni would do for research. Binti smears it with otjize to make the scar disappear.
Over the next few weeks, Binti tracks down the ingredients to make otjize. She buys oil in the market and harvests clay from the forest. When the concoction is ready, Binti showers off all the otjize from home, sobbing. She wonders if her okuoko will grow like hair, and she’s sad that she can’t braid the 10 okuoko in the pattern of her family. When it’s dark, Binti panics, unsure if she made real otjize. She realizes that if she can’t make otjize here, she’ll have to change—but what she scoops out of her jar seems real and makes her cry. Then, she visits Okwu. Okwu is thrilled to see Binti covered in thick otjize again and holds out a tentacle that was burned during an experiment. Binti is nervous, but she covers the burn in okuoko. She knows that the Meduse respect her for her otjize, so she wonders what Okwu thinks about her now. Binti whispers that she knows the Meduse are traditional, but that Okwu is her only friend. Okwu tells Binti to call home but assures her that they’re friends no matter what. It vibrates a tentacle, and Binti’s okuoko vibrate in response, which Okwu says means that they’re family. When Binti rubs off the otjize from the tentacle, the burn is gone. Later, Binti calls home, and her mother answers.
